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Re: Carbide Insert Nomenclature?
Maybe one of the mods. could upload it here in our files section? :)
Thanks for considering my request. --- In 7x12minilathe@..., "paul_probus" <paul_probus@...> wrote:
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Re: Carbide Insert Nomenclature?
You guys are the best! Thanks everyone for sharing. I like to study,
and this gives me lots of information to get going with. --- In 7x12minilathe@..., "paul_probus" <paul_probus@...> wrote: one I offered up. I think the magic page issimplefor Indexable Inserts" at: (forthough!me,would > |
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Re: Carbide Insert Nomenclature?
The link to the "cheat sheet" I posted is far handier and easier to
follow, IMHO. Paul --- In 7x12minilathe@..., "Charles E. Kinzer" <ckinzer@...> wrote: I offered up. I think the magic page is for Indexable Inserts" at: which has a very nice description of things that gets into a lot of fine detail. It's probably worth printing out and keeping handy with the catalogs. their drop down boxes that relates to the letters (like "TNMG") and put it below in case anyone finds it helpful in this forum in this form. Or in this form in this forum. the styles are what was on the site and are not typos. between a TNMG and a TPG insert nomenclature. They frequently have some good deals on "surplus"9X20 > design. Gadgetbuilder has one he made on his site as well. Inask for ordoesn't > specify. I know I want something that doesn't require anangled holder,(making my(for me,would bebrass, and thedesignations meanthem? > After looking around, I haven't had much luck. Besides, theanything but |
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Re: Carbide Insert Nomenclature?
Here is a link, since I could not upload a file into the Files
section of the group. It is one of my groups and you'll have to join before you can see it. Sorry, I would have uploaded it here, but like I said earlier... It may not be the most up-to-date (if they've come up with any other kinds of inserts), but it should give you a good reference for the majority of the inserts made. Paul --- In 7x12minilathe@..., "clypeaster55" <clypeaster55@...> wrote: gathering the materials, it occured to me that I have no idea what to askfor or order when it comes to the carbide insert. Gadgetbuilder usesa "TNMG"? insert, which he says needs a 5 degree titl, and Bedair's doesn'tholder, since I would like to get a few of these to experiment with(making my own holders, thread tools, etc.). Keeps things nice and simple(for me, that's a good thing!). I would however, like an insert that wouldbe good for general use with a variety of metals (CS, 6061, brass,and the occaisional SS).mean and where can I find a simple explanation of the types andonly "T" codes I know about is "TGIF", and I don't think that cuts anythingbut the end of the week! At least it only comes in one size though! |
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Re: Way Wear, Hard Gibs
Marty N
It's an Albion box for an Enfield Mike.
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----- Original Message -----
From: Michael Taglieri To: 7x12minilathe@... Sent: Wednesday, March 07, 2007 1:56 AM Subject: Re: [7x12minilathe] Re: Way Wear, Hard Gibs Marty, what's the vehicle that your "gearbox of English design from the 40's" is used in? I have a similar English design (from the 30's) on my Norton Commando motorcycle. It has worked fine for 2 decades with occasional loving care despite being on a bike that puts out far more horsepower than it was designed for, and it also uses a shaft within a shaft, which put the input shaft from the engine on the same side as the output shaft to the rear wheel so manufacturers could add gearboxes to bikes that previously didn't have them. However, the Norton gearbox design has replaceable bronze bushings inside the outer shaft so the inner one doesn't wear significantly (and custom bushings made on a minilathe can solve the problem if it does). I'm surprised that the design of yours had steel rubbing on steel. A steel gib rubbing against a cast iron bed (which is porous and tends to soak up oil) isn't going to have significant wear, but a steel shaft turning at several thousand RPM inside another steel shaft seems like a pretty clueless design. Mike Taglieri miket--nyc@... Everyone has his reasons. - Jean Renoir "The Rules of the Game" On Tue, 6 Mar 2007 22:16:37 -0600 "Marty N" <martyn@...> writes: > How about we leave it at this..."everyone has his reasons". ;) > > Everyone's needs, abilities, wishes and ideas will differ and > perhaps there is no "holly grail" of gibs or any other part for that > matter. Thing is that I've just never experienced a single case in > the world of mechanical devices where attention to what seems like > the trivial pursuits of overly complex to others, excellence to me, > hasn't paid me back in triple with results. > > Unrelated example. I have a gearbox of English design from the 40's > that uses a stacked shaft arrangement, shaft within a shaft. I was > going threw these at a rate of about 2500 miles per shaft. They were > made from 1045 and through hardened but the finish was rougher than > what you see today and the clearance sloppy but by design but to > print and it used "00" grease as a lubricant. I had the outer shaft > honed "round", something it wasn't before, and smooth, 20 Ra. Then > had the inner shaft ground round and hard chromed then reground for > a clearance of .0015". stock was about .008" average. I switched > lubricants to a polyol ester oil..Redline Shock Proof Heavy. > Everybody and there brother told me that I fit it too tight, > finished it too smooth, lubricant was too light, chrome wouldn't > hold up and was too hard and would abrade the untreated inner shaft > and so on and so on. That was in 2002 and the box hasn't been apart > since. It also does something it never did before, shift cleanly. > Project cost me about $100 in services and parts. Each broken or > seized shaft set cost me that much every few months before that and > meant weeks of down time each and every go at it. |
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Re: Way Wear, Hard Gibs
Hi Mike,
Yep, I think you've established the rear slide wears most but not rapidly. I'm still planning to shim & lap my original slides like you. I did forget the other major source of lifting forces on that back slide - a traditional knurling tool being pressed into the work via toolpost pressure. I take it you don't use one of those. :-) John --- In 7x12minilathe@..., Michael Taglieri <miket-- nyc@...> wrote: usually Gravitywhile using a milling adapter with the carriage stationary. of theworks the other way.Actually, this isn't quite true. There's a force lifting the rear carriage whenever the tool is cutting the outside of the work(i.e., not when making a facing cut). Therefore, you should expect the rearto wear more than the front on the bottom (and perhaps the front to wearmore on the top).using the original gibs. Within a year or so, the rear of the carriage gota bit loose and I had to take out 1-2 thousandths of shimming, but thefront didn't need that treatment until late 2006. Obviously, this isn'ttoo shabby, even for the rear, but I still expect it will always wearmore than the front. If the underside of the rear ever wears to thepoint that some parts are looser than others, I can just relap the rearof the bed by sliding the carriage back and forth with abrasives on theslightly.
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Re: Carbide Insert Nomenclature?
Charles E. Kinzer
I think that Carbide Depot site is much handier than the first one I offered up. I think the magic page is
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I also just tripped over this page called "Identification System for Indexable Inserts" at: which has a very nice description of things that gets into a lot of fine detail. It's probably worth printing out and keeping handy with the catalogs. From the Carbide Depot site you provided, I took the data from their drop down boxes that relates to the letters (like "TNMG") and put it below in case anyone finds it helpful in this forum in this form. Or in this form in this forum. SHAPE: A - 85 degree parallelogram C - 80 degree diamond D - 55 degree diamond O - octagon R - round S - square T - triangle V - 35 degree diamond W - 80 degree trigon RELIEF ANGLE: N - 0 degree relief angle B - 5 degree relief angle C - 7 degree relief angle P - 11 degree relief angle D - 15 degree relief angle E - 20 degree relief angle F - 25 degree relief angle TOLERANCE: A - .0002"/.001"/.001" C - .0005"/.005"/.001" E - .001"/.001"/.001" G - .001"/.001"/.001" K - .005"/.001"/.002" M - molded tolerance U - utility tolerance STYLE: - no hole/no chip breaker (no 4th letter) A - straight hole/no chipbreaker B - countersunk hole/no chipbreaker E - no hole/no chipbreaker F - no hole/2-sided chipbreaker G - straight hole/2-sided chipbreaker H - countersunk hole/1-sided chipbreaker M - straight hole/1-sided chipbreaker P - straight hole/hi positive chipbreaker R - no hole/1-sided chipbreaker S - straight hole/hi positive chipbreaker T - countersunk hole/1-sided chipbreaker W - countersunk hole/no chipbreaker Z - straight hole/hi positive chipbreaker The one duplication in the tolerance and the many duplications in the styles are what was on the site and are not typos. A cheat sheet really does make it easier to see the difference between a TNMG and a TPG Chuck K. ----- Original Message -----
From: roylowenthal To: 7x12minilathe@... Sent: Tuesday, March 06, 2007 6:27 PM Subject: [SPAM] [7x12minilathe] Re: Carbide Insert Nomenclature? Carbide Depot's site has a pretty good section on decoding the insert nomenclature. They frequently have some good deals on "surplus" tooling. Not affiliated, just a satisfied customer. Roy --- In 7x12minilathe@..., "clypeaster55" <clypeaster55@...> wrote: > > I am going to build a ball/radius cutter similar to Bedair's 9X20 > design. Gadgetbuilder has one he made on his site as well. In gathering > the materials, it occured to me that I have no idea what to ask for or > order when it comes to the carbide insert. Gadgetbuilder uses a "TNMG"? > insert, which he says needs a 5 degree titl, and Bedair's doesn't > specify. I know I want something that doesn't require an angled holder, > since I would like to get a few of these to experiment with (making my > own holders, thread tools, etc.). Keeps things nice and simple (for me, > that's a good thing!). I would however, like an insert that would be > good for general use with a variety of metals (CS, 6061, brass, and the > occaisional SS). > > So... my real question is, what do all these "Txxx" designations mean > and where can I find a simple explanation of the types and > nomenclature? Can you buy the screws they need together with them? > After looking around, I haven't had much luck. Besides, the only "T" > codes I know about is "TGIF", and I don't think that cuts anything but > the end of the week! At least it only comes in one size though! > > Any advice is MUCH appreciated. > |
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Re: Way Wear, Hard Gibs
Michael Taglieri
On Wed, 07 Mar 2007 01:36:40 -0000 "born4something"
<ajs@...> writes: Actually, this isn't quite true. There's a force lifting the rear of the carriage whenever the tool is cutting the outside of the work (i.e., not when making a facing cut). Therefore, you should expect the rear to wear more than the front on the bottom (and perhaps the front to wear more on the top). When I lapped my dovetails and the underside of the bed in 2002, I changed the gib retention system under the carriage to shims, using the original gibs. Within a year or so, the rear of the carriage got a bit loose and I had to take out 1-2 thousandths of shimming, but the front didn't need that treatment until late 2006. Obviously, this isn't too shabby, even for the rear, but I still expect it will always wear more than the front. If the underside of the rear ever wears to the point that some parts are looser than others, I can just relap the rear of the bed by sliding the carriage back and forth with abrasives on the underside, after removing enough shims in the back so it drags slightly. Mike Taglieri miket--nyc@... Everyone has his reasons. - Jean Renoir "The Rules of the Game" |
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Re: Way Wear, Hard Gibs
Michael Taglieri
Marty, what's the vehicle that your "gearbox of English design from the
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40's" is used in? I have a similar English design (from the 30's) on my Norton Commando motorcycle. It has worked fine for 2 decades with occasional loving care despite being on a bike that puts out far more horsepower than it was designed for, and it also uses a shaft within a shaft, which put the input shaft from the engine on the same side as the output shaft to the rear wheel so manufacturers could add gearboxes to bikes that previously didn't have them. However, the Norton gearbox design has replaceable bronze bushings inside the outer shaft so the inner one doesn't wear significantly (and custom bushings made on a minilathe can solve the problem if it does). I'm surprised that the design of yours had steel rubbing on steel. A steel gib rubbing against a cast iron bed (which is porous and tends to soak up oil) isn't going to have significant wear, but a steel shaft turning at several thousand RPM inside another steel shaft seems like a pretty clueless design. Mike Taglieri miket--nyc@... Everyone has his reasons. - Jean Renoir "The Rules of the Game" On Tue, 6 Mar 2007 22:16:37 -0600 "Marty N" <martyn@...> writes: How about we leave it at this..."everyone has his reasons". ;) |
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Re: Way Wear, Hard Gibs
Fair 'nuff Marty.
I get down to detail in electronics stuff where I know my territory. No qualms about ripping commercial gear apart and redesigning. This stuff is out of my territory and went counter-intuitive for me so I figured I'd raise the query. Later, John --- In 7x12minilathe@..., "Marty N" <martyn@...> wrote: perhaps there is no "holly grail" of gibs or any other part for that matter. Thing is that I've just never experienced a single case in the world of mechanical devices where attention to what seems like the trivial pursuits of overly complex to others, excellence to me, hasn't paid me back in triple with results. 40's that uses a stacked shaft arrangement, shaft within a shaft. I was going threw these at a rate of about 2500 miles per shaft. They were made from 1045 and through hardened but the finish was rougher than what you see today and the clearance sloppy but by design but to print and it used "00" grease as a lubricant. I had the outer shaft honed "round", something it wasn't before, and smooth, 20 Ra. Then had the inner shaft ground round and hard chromed then reground for a clearance of .0015". stock was about .008" average. I switched lubricants to a polyol ester oil..Redline Shock Proof Heavy. Everybody and there brother told me that I fit it too tight, finished it too smooth, lubricant was too light, chrome wouldn't hold up and was too hard and would abrade the untreated inner shaft and so on and so on. That was in 2002 and the box hasn't been apart since. It also does something it never did before, shift cleanly. Project cost me about $100 in services and parts. Each broken or seized shaft set cost me that much every few months before that and meant weeks of down time each and every go at it. overly complex ;) and win being that. Hold over from racing days. complex. once shimmed properly. I haven't shimmed yet but plan to. I amup by twisting them all over the place because they don't understandwhat they are doing. Agreed they need some thread seal to stay put.Mine fell apart during shipping. But gee that's easy.screws that holdto theadjustment. This istwo dogthe mostin the bestthat only theunderside, and onlyhigh enoughThis is a bitshims is anthe gib asshims in the packto removeis so softlapped the gibs IIf your goingwithout > perforation where extremely fine adjustment can be made. 6)is .375" thick andwould down to theiron has 23%spec to) hasas brass on |
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Re: HF Lathes
--- In 7x12minilathe@..., "Aaron Pasteris"
<aarons_groups@...> wrote: ... The Harbor freight is actually 2" shorter than the others and moreexpensive so stay away if possible. ...I'm sure Mr. Pasteris meant to say 4" shorter here. The 7x10 is more honestly a 7x8, while the 7x12 is an honest 7x12. Speaking as a 7x8 owner, on such a short lathe an extra 4" is very desirable. |
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Re: Homier vs Cummins - Better Buy?
I actually called to order an 8x12 last weekend and found the price
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had gone up, it is now $499, and it's on back order with no expected date. So instead of waiting, or going bigger, I decided to save some money and go with a 7x12. Ed I too was going for Cummins but have decided to go for the harbor |
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Re: Way Wear, Hard Gibs
Marty N
How about we leave it at this..."everyone has his reasons". ;)
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Everyone's needs, abilities, wishes and ideas will differ and perhaps there is no "holly grail" of gibs or any other part for that matter. Thing is that I've just never experienced a single case in the world of mechanical devices where attention to what seems like the trivial pursuits of overly complex to others, excellence to me, hasn't paid me back in triple with results. Unrelated example. I have a gearbox of English design from the 40's that uses a stacked shaft arrangement, shaft within a shaft. I was going threw these at a rate of about 2500 miles per shaft. They were made from 1045 and through hardened but the finish was rougher than what you see today and the clearance sloppy but by design but to print and it used "00" grease as a lubricant. I had the outer shaft honed "round", something it wasn't before, and smooth, 20 Ra. Then had the inner shaft ground round and hard chromed then reground for a clearance of .0015". stock was about .008" average. I switched lubricants to a polyol ester oil..Redline Shock Proof Heavy. Everybody and there brother told me that I fit it too tight, finished it too smooth, lubricant was too light, chrome wouldn't hold up and was too hard and would abrade the untreated inner shaft and so on and so on. That was in 2002 and the box hasn't been apart since. It also does something it never did before, shift cleanly. Project cost me about $100 in services and parts. Each broken or seized shaft set cost me that much every few months before that and meant weeks of down time each and every go at it. I have at least 20 experiences like that. T'is in my nature to be overly complex ;) and win being that. Hold over from racing days. Your right though John, not everyone's cuppa. Marty ----- Original Message -----
From: born4something To: 7x12minilathe@... Sent: Tuesday, March 06, 2007 9:23 PM Subject: [7x12minilathe] Re: Way Wear, Hard Gibs Hi Marty, Gotta go with Roy on this one. You're making things overly complex. This isn't a big lathe. The existing plates are quite adequate once shimmed properly. I haven't shimmed yet but plan to. I am temporarily getting reasonable performance from the stock arrangement once properly adjusted. Admittedly many stuff them up by twisting them all over the place because they don't understand what they are doing. Agreed they need some thread seal to stay put. Mine fell apart during shipping. But gee that's easy. John --- In 7x12minilathe@..., "Marty N" <martyn@...> wrote: > > > > I just couldn't understand why anyone would go out of their way > (poor pun) to use hardened strips and see it as an improvement > rather than a potential risk. > > John > > Hi John: > > I liked the pun :) > > Here's my personal thought on the "why". 1.) The three cap screws that hold > the gib opposed to the two dog points can provide zero preload to the > fasteners, thus they are at will to move, won't hold adjustment. This is > easy enough to take care of with a bit of blue Loctite. 2) The two dog > points are not equidistant between cap screws, thus, even with the most > meticulous setting the gib is bent to an arc if ever so slight in the best > of cases and flat bowed silly in the worst of it. This means that only the > leading and trailing edges are in contact with the ways underside, and only > the outside "points" of that. This makes unit force over area high enough > to, a) pierce the oil film b.) scrap the oil from the way. This is a bit > more difficult to fix. Replacement of the dog points with shims is an > alternative however the material the gib is made of is so soft that in my > first attempt at it with the half hard 260 brass I used dented the gib as > easily as a finger nail dents pine boards. I had cut the brass into two > pieces, one each side of the center cap screw as the fine adjustment needed > here precluded, for me, individually making holes for all shims in the pack > required. This leads to misalignment by the depth of the dent. Later when I > lapped the stock gibs it took nearly .004" after local contact to remove > said dents. 3.) Even when a full shim is in play the material is so soft > that it flexes silly under moderate pressures. 4.) When I lapped the gibs I > took .008 of this little critters, after straightening, to get full contact > with the lapping plate, wavy, bent, bowed, dented...junk. 5.) If your going > to fix it, then, fix it. 5.) Made from some hardened material, such as A2, > makes it stiff enough to loose the center cap, use a shim without > perforation where extremely fine adjustment can be made. 6) Because my > Southbend uses a gib 10" long held with two cap screws, is .375" thick and > is hardened, ribbed iron and doesn't flex or bow over the cantilever. So > it's not a poke in the dark. 7.) On my machine built 5/26/1956 shows zilch > for wear after 50 years. 8) I'll copy a proven design and would down to the > cantilever if I had enough room :) 9.) Because hard steel on iron has 23% > less friction than iron on brass. And hard chromed (what mine spec to) has > half the static friction of iron on iron and will not gall. In fact hard > chrome on iron has about half the frictional coefficient dry as brass on > iron does lubricated. > > Just thoughts. > > Marty > |
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Re: Homier vs Cummins - Better Buy?
--- In 7x12minilathe@..., "ednsu" <edo@...> wrote:
I too was going for Cummins but have decided to go for the harbor freight model 44859 8x12 which is the same one sold by lathemaster. It is really an 8x14 and when on sale for 439.00 a much more solid tool at about 300 lbs.look it up and also check the websites on it. Almost all 7x are of same lighter design. The 8x is very different. Chris... |
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Re: Way Wear, Hard Gibs
Marty N
Does this mean crossed roller slides on Haas and Mazak turning centers should wear out in a week, rollers hardened to 52 to 55C running on rails equally hard? Open lubrication and flood cooling!
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Lathes rarely "wear out" because of use but because of "misuse" and poor up keep. Keep it clean, keep it aligned, keep it oiled, keep it's operation within it's envelope. Ian, I'm not saying things won't wear. I'm saying the by the time you need to replace a bed because the underside of the way wore out from hard gibs your grand kids will have used it a life time. I adjust these soft gibs about 3 times a year on my HF and about once every five years on my Southbend's hard gibs and it's 51 years old. It's not a question of IF but of when and does when matter if it isn't in your life time. Perspective if you see what I mean. Myself, there is more plus than minus to a set up I can keep in adjustment because of low wear rates and the ability to maintain good lubrication due to good geometry. John, a friend, who rebuilds a fair amount of machines has a 10" Clausing underway at the moment. He has to replace a broken gib on a cross slide. As a machine shop I asked him why not just "whip one up"? His reply was that by the time he cuts the blank, has it hardened and grinds it in he has more that the $50 it will take to buy it. Yes they have hard gibs and no they don't replace iron castings 5 to 1 because of it. What's the difference between a current model Honda that will easily go half a million miles between rebuilds and a 60 Chevy that if using today's lubrication might make it 150,000, maybe ( and in the day struggled for 100,000)? Answer! Fit, finish; harder, smoother more precise finishes of all internal components. They run hard as hell chilled iron camshaft journals straight in the cast aluminum heads. Marty ----- Original Message -----
From: steam4ian To: 7x12minilathe@... Sent: Tuesday, March 06, 2007 8:47 PM Subject: [7x12minilathe] Re: Way Wear, Hard Gibs G'day Marty,John, Gianni et al. To extrapolate what Marty is saying suggests a lathe should never wear out. Unfortunately that is not the case. The contaminants have to be factored into the discussion. Small swarf and dust particles will act as abrasives and will selectively attach the softer material; in Gianni's proposal the cast iron bed. Journal type bearings have a hard metal shaft running in a soft bearng shell. The soft metal, Babbit, has the capacity to envelop the abrasive particles without their abrading the shaft. To use Mary's analogy the big end bearings, etc have a babbit coated shell. Older lathes have white metal bearings in the headstock, even some recent precision lathes. The world's biggest bearings operate on this principle. To extrapolate my argument we would be better off using brass gibs with a babbit coating. (Some Old Timer may recall just such an application.) Come to think of it, I recall that steam loco cross head slippers are white metalled (coated with babbit). Not having any bronze I have made some brass bearing bushes which I have tinned (97% tin solder), these seem to work well. For me I would find something better to do with HSS than make gibs out of it. One good turn deserves another. Regards to all, Ian --- In 7x12minilathe@..., "born4something" <ajs@...> wrote: > > Yep, you may well be correct - it may be a non-issue. Then again, > without a pretty good reason, I personally wouldn't do it just to > find out. > > > John > > > > --- In 7x12minilathe@..., "Marty N" <martyn@> wrote: > > > > Gianni wrote: > > > > My idea is to replace the saddle gibs with a pair of HSSco flats I > brought in a surplus shop > > > > John replies: > > > > Flat for those strips is good. I'm not so sure about hard. That > will ensure the eventual wear will be born by the ways rather than > the gib strips. I know which I'd rather maintain or replace. :-) > > > > Marcello replies: > > > > I would not use HSS cobalt flats to make saddle gibs: I fear that > would mean all the wear will be on the saddle. > > > > Marty replies: > > > > Hang out for awhile. This starts like it's going nowhere in > particular. > > > > You have a motor with 100,000 miles on it and the rings go south. > You pull the head and measure the cylinder ridge and find you > have .005" wear. By extrapolation we could say that .0005" happens > every 10,000 miles. > > > > > > So here are the questions. Why do we think that tool steel, flat, > smooth gibs will accelerate wear of the iron bed? Even if it did and > did so at the same rate per distance traveled, how long would you > have to run a lathe to produce 42 million passes over the bed of at > least 3.5" distance per pass? > > > > IF your thinking that there is no correlation between the examples > list...you may be right...the lathe has 60 fold greater viscosity, > runs 530 degrees cooler and does so at something less than 2% of the > unit loading. Edge goes to the lathe. > > > > > > > |
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Homier vs Cummins - Better Buy?
I'm looking at buying a 7x12 and am trying to decide between the
Homier and the Cummins. It appears the Cummins, although $100 more comes with more accessories, but Homier has an accessory kit for $100. Which one do you think is the better deal? Shipping is about the same. |
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Re: Way Wear, Hard Gibs
Hi Marty,
Gotta go with Roy on this one. You're making things overly complex. This isn't a big lathe. The existing plates are quite adequate once shimmed properly. I haven't shimmed yet but plan to. I am temporarily getting reasonable performance from the stock arrangement once properly adjusted. Admittedly many stuff them up by twisting them all over the place because they don't understand what they are doing. Agreed they need some thread seal to stay put. Mine fell apart during shipping. But gee that's easy. John --- In 7x12minilathe@..., "Marty N" <martyn@...> wrote: that hold the gib opposed to the two dog points can provide zero preload tothe fasteners, thus they are at will to move, won't hold adjustment.This is easy enough to take care of with a bit of blue Loctite. 2) The twodog points are not equidistant between cap screws, thus, even with themost meticulous setting the gib is bent to an arc if ever so slight inthe best of cases and flat bowed silly in the worst of it. This means thatonly the leading and trailing edges are in contact with the ways underside,and only the outside "points" of that. This makes unit force over area highenough to, a) pierce the oil film b.) scrap the oil from the way. This isa bit more difficult to fix. Replacement of the dog points with shims isan alternative however the material the gib is made of is so softthat in my first attempt at it with the half hard 260 brass I used dented thegib as easily as a finger nail dents pine boards. I had cut the brassinto two pieces, one each side of the center cap screw as the fineadjustment needed here precluded, for me, individually making holes for all shims inthe pack required. This leads to misalignment by the depth of the dent.Later when I lapped the stock gibs it took nearly .004" after local contact toremove said dents. 3.) Even when a full shim is in play the material isso soft that it flexes silly under moderate pressures. 4.) When I lappedthe gibs I took .008 of this little critters, after straightening, to getfull contact with the lapping plate, wavy, bent, bowed, dented...junk. 5.) Ifyour going to fix it, then, fix it. 5.) Made from some hardened material,such as A2, makes it stiff enough to loose the center cap, use a shim withoutBecause my Southbend uses a gib 10" long held with two cap screws, is .375"thick and is hardened, ribbed iron and doesn't flex or bow over thecantilever. So it's not a poke in the dark. 7.) On my machine built 5/26/1956shows zilch for wear after 50 years. 8) I'll copy a proven design and woulddown to the cantilever if I had enough room :) 9.) Because hard steel on ironhas 23% less friction than iron on brass. And hard chromed (what mine specto) has half the static friction of iron on iron and will not gall. Infact hard chrome on iron has about half the frictional coefficient dry asbrass on iron does lubricated. |
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Re: HF Lathes
Hi,
From what I understand they are mostly made in the same factory but to individual distrubutor spec. That is, the distributor has some freedom to specify fine details like power filtering, way hardening, tolerances, included options, paint colour, etc. Some of these (colour?) are probably trivial but there are differences to shop on. Not the least is price and customer service. John --- In 7x12minilathe@..., "film2paper" <film2paper@...> wrote: thing HF sells that isn't imported is time. You can find a nice usedMade in America machine on eBay or local auctions, but it might take abit of time and many are true "labors of love" - in the best sense ofthe phrase.to help!Harbor Freight lathestimereally ok for light duty beginning work like brass knobs andslottingsome brass etc.? My work arounds are driving me nuts and it's tocaseget a lathe. I have some huge heavy duty woodworking machines, someiron, and I am reluctant to get any of the import machines.I plan to make some knurled knobs, an inch or less in dia. and lens mounting flanges not more than three inches. A 7x12 would beare they all made in the same manufacturing plants. I live a hundred |
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Re: Way Wear, Hard Gibs
Marty N
I just couldn't understand why anyone would go out of their way
(poor pun) to use hardened strips and see it as an improvement rather than a potential risk. John Hi John: I liked the pun :) Here's my personal thought on the "why". 1.) The three cap screws that hold the gib opposed to the two dog points can provide zero preload to the fasteners, thus they are at will to move, won't hold adjustment. This is easy enough to take care of with a bit of blue Loctite. 2) The two dog points are not equidistant between cap screws, thus, even with the most meticulous setting the gib is bent to an arc if ever so slight in the best of cases and flat bowed silly in the worst of it. This means that only the leading and trailing edges are in contact with the ways underside, and only the outside "points" of that. This makes unit force over area high enough to, a) pierce the oil film b.) scrap the oil from the way. This is a bit more difficult to fix. Replacement of the dog points with shims is an alternative however the material the gib is made of is so soft that in my first attempt at it with the half hard 260 brass I used dented the gib as easily as a finger nail dents pine boards. I had cut the brass into two pieces, one each side of the center cap screw as the fine adjustment needed here precluded, for me, individually making holes for all shims in the pack required. This leads to misalignment by the depth of the dent. Later when I lapped the stock gibs it took nearly .004" after local contact to remove said dents. 3.) Even when a full shim is in play the material is so soft that it flexes silly under moderate pressures. 4.) When I lapped the gibs I took .008 of this little critters, after straightening, to get full contact with the lapping plate, wavy, bent, bowed, dented...junk. 5.) If your going to fix it, then, fix it. 5.) Made from some hardened material, such as A2, makes it stiff enough to loose the center cap, use a shim without perforation where extremely fine adjustment can be made. 6) Because my Southbend uses a gib 10" long held with two cap screws, is .375" thick and is hardened, ribbed iron and doesn't flex or bow over the cantilever. So it's not a poke in the dark. 7.) On my machine built 5/26/1956 shows zilch for wear after 50 years. 8) I'll copy a proven design and would down to the cantilever if I had enough room :) 9.) Because hard steel on iron has 23% less friction than iron on brass. And hard chromed (what mine spec to) has half the static friction of iron on iron and will not gall. In fact hard chrome on iron has about half the frictional coefficient dry as brass on iron does lubricated. Just thoughts. Marty |
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Re: HF Lathes
Aaron Pasteris
For the 7x lathes the cheapest is the Homier ($299) but it comes with no tooling.
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Next is the Cummins for $399 with a good accessory package The Harbor freight is actually 2" shorter than the others and more expensive so stay away if possible. For parts and accessories - www.littlemachineshop.com (great service) Aaron ----- Original Message -----
From: film2paper To: 7x12minilathe@... Sent: Tuesday, March 06, 2007 9:05 PM Subject: [7x12minilathe] Re: HF Lathes --- In 7x12minilathe@..., Druid Noibn <druid_noibn@...> wrote: > > Hi, > > All of the lathes here are "imported" machines. The only thing HF sells that isn't imported is time. You can find a nice used Made in America machine on eBay or local auctions, but it might take a bit of time and many are true "labors of love" - in the best sense of the phrase. > > OK what size lathe or work do you plan on doing? Many are here to help! > > Take care, > DBN > > > > film2paper <film2paper@...> wrote: > Hello all, I have a shop but not a lathe. Is the Harbor Freight lathes > really ok for light duty beginning work like brass knobs and slotting > some brass etc.? My work arounds are driving me nuts and it's time to > get a lathe. I have some huge heavy duty woodworking machines, case > iron, and I am reluctant to get any of the import machines. > > > > > > > --------------------------------- > 8:00? 8:25? 8:40? Find a flick in no time > with theYahoo! Search movie showtime shortcut. > > I plan to make some knurled knobs, an inch or less in dia. and some lens mounting flanges not more than three inches. A 7x12 would be large enough to cover what I plan to do. Which brand is better or are they all made in the same manufacturing plants. I live a hundred miles from Grizzly Imports too, but only a couple of miles from a harbor freight store. > |
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