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Re: Boring bar setup question
John Lindo
Hello Ryan. You did not mention if this was a through hole that you have problems with. If it is a blind hole,a boring bar with a flood coolant hole may work,to wash out the chips. I agree with the comments about rake angles. IMO carbide for cutting听aluminium never seems to work well.the chips tend to stick to the tip even with WD 40 as a cutting lubricant. Try using a home made boring bar with a HSS tool bit.,and or a D bit drill made out of 3/4 " drill rod. Just for interest,how did you get the hole roughed out in the first place? If a through hole have you thought about boring from both ends,skimming the outside diameter and using a soft jaws in a 3 jaw chuck, or a 4 jaw chuck, using a Dial indicator to get the concentricity when boring from the other end. John L Spain.
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Re: Newb question about 1/8" cutting tools
开云体育I agree with the QCTP thought, couple of reasons, 听FIRST, for me it 听was setting tool bit height! I鈥檓 NOT a machinist, bought a 7X five years ago and the first 鈥渦pgrade鈥� was the Quick Change Tool Post. 听Over the years I鈥檝e picked up a couple more tool holders, makes setting the height and tool changes a POC (piece of cake) I went the 鈥淐heep鈥� HF 录鈥� tool route.鈥� mistake鈥︹��. Then I bought a 鈥減re-ground鈥� set from Grizzly鈥︹��.. beautiful (expensive) wood case, real cutters! Of course I 听jammed em鈥�, dropped em鈥�, galled鈥�. used and abused em鈥�, 听they got dull! What to do now, learn to grind my own. As a concept, up there with sliced bread. One can become听 adequate with a cheap 6鈥漡rinder, and a 听little practice! 听LMS has (2) two items that were invaluable to me during my 鈥渟teep鈥� learn curve. 听This video鈥� 听 and these HSS blanks鈥�. 听 All The Best, 听 Allen, on an island in SE Alaska 听 From: 7x12minilathe@... [mailto:7x12minilathe@...]
On Behalf Of Exibar
Sent: Saturday, February 02, 2013 7:38 PM To: 7x12minilathe@... Subject: RE: [7x12minilathe] Newb question about 1/8" cutting tools 听
I second the QCTP setup....听 I got one last year and I honestly don't know what I'd be doing without it right now.... 听 From:
7x12minilathe@... [mailto:7x12minilathe@...] On Behalf Of Jim Dunmyer 听 听 Jeremy, Do yourself a huge favor and get a QCTP setup from LMS. See: for their selection; I don鈥檛 know which one you need right offhand, but they鈥檙e very helpful if you ask. While you鈥檙e at it, buy a few HSS toolbits and grind them according to your needs. 听 听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听 <> 听 From: cptwinderatgmaildotcom Sent: Saturday, February 02, 2013 7:16 PM Subject: [7x12minilathe] Newb question about 1/8" cutting tools 听 听 When I
purchased my lathe, I also purchased a few sets of cutting tools: 听
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Re: tailstock Cam lock kit and F/O/R switch change
Jim Dunmyer
开云体育Mike,
When I had my H.F. lathe, I bought a 17mm combination wrench at a flea
market, then cut it about in half with an abrasive wheel. The box end of it is
bent at an angle, and it hangs on the T.S. clamp nut. You can usually
loosen/tighten the nut w/o actually removing the wrench at all. If you do have
to move it, one additional swing will do the job. It鈥檚 nearly as fast as a true
cam-lock T.S., and clamps better. At least, it worked better than the cam-lock
setup on my Micro-Mark 7X14.
听
听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听
<>
听 From: Exibar
Sent: Sunday, February 03, 2013 12:05 AM
Subject: [7x12minilathe] tailstock Cam lock kit and F/O/R switch
change 听
听
HI All! 听听听 I've been making some parts lately and have had some luck selling them as well.听 Enough to buy some new hop-ups for my 7x12 Cummings lathe :-)
My F/O/R switch is acting up, and I'm thinking that I'd rather have a rotary type switch instead of a toggle, like the one that's on the micromark 7x14... anyone make this swap?听听 I'll probably just wind up going with a stock replacement, unless the swap is easy?
I'm also thinking about a Tailstock cam lock kit.听 I see LMS has them for $30...听 Does the cam lock kit rally get the tailstock clamped down tight enough so it doesn't move?听 will installing this kit throw off he alignment of the Tailstock?听 My TS is perfectly aligned right now, I really dont' want to go through that trouble again of lining it back up... or worse I really don't want it to be thrown out of alignment higher or lower :-(
thanks! 听 Mike B |
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Re: Boring bar setup question
开云体育Hi Ryan !
For good results, boring holes are typically limited to about 1.5-2x boring bar diameter. As such, a 3/8 boring bar is only good to about 1/2 inches. After this it will chatter with variable results. All lathe tools work well only upto about 1-3x their size. Ie a 1/2 inch tool will only work well to 1-1.5 inches deep. However.. Alu is easy. Your problem is rake. CCMT is 7 degrees positive and you need to maintain this, *especially* when doing deep bores. With a -5 degrees boring bar, you are losing the benefits of the insert, and greatly increasing the problems of the overly long, slim, thin bar. It *can* be done with a 3/8 in alu but not well, imo. You need to have at least 7 degrees rake, even听 a bit more. If you can make (buy) another bar (any steel) of near .7 inches, and have the bit be at zero-1 degree rake, it will go vastly better. For alu, at .75 inches or about 18 mm, I would recommend about 1000 rpm, 0.1 - 0.06 mm cuts. 听 -- -hanermo |
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Re: Boring bar setup question
Thanks! I'll read the .pdf's when I get home.
One thing I see from the thread is I may have got the wrong inserts. I probably should have got 20.50's with the .008" nose instead of 20.51's with an .016" nose. WAM <ajawam2@...> wrote: 听 There's a great article on boring bar chatter: |
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Re: Newb question about 1/8" cutting tools
开云体育Many complain about stock carbide
stuff.
This is usually because the tools are not the right ones for the lathe ! Many cheap carbide sets are 0% and so on of an angle (rake). In industrial use, negative angles are common. This is because negative angle tools last lots longer, and produce parts very well for a long time, when sufficient tool pressure (derived from HP and rigidity) are used. These are impossible to utilise on common cheap 7x-11x lathes. A small, low powered 7x needs either HSS or a positive angle carbide insert, CCMT is a common, well known, very succesful, solution. 7 degrees positive rake. I use these on both 7x and 12x industrial stuff with great results. Industrial stuff often needs high pressure and heat to work well. Minimum cutting depths are 0.2- .3 or so mm in medium (100MM) diameters. This needs several Hp. 听 -- -hanermo |
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Re: Boring bar setup question
There's a great article on boring bar chatter:
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A lot of math tho... Long thin boring bars are prone to that. Some comments here: Do you have a larger diameter boring bar? That may help... Also - tunable boring bar article: Basically add some mass to change the resonant frequency ... Ryan_Hodges wrote: Hi group! |
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Boring bar setup question
Hi group!
I recently bought a 3/8 indexable boring bar that uses CCMT inserts. The bar has 5掳 negative built in. I'm using CCGT high polish 21.51 inserts and have a huge amount of chatter. I'm doing a 3/4 inch diameter hole just over 3" deep in 6161 aluminum. I've tried the bar above center and on center. Above seems to chatter a bit less but I still can't get a nice cut. Wrong insert, bad setup? Do I need a different bar? Just too deep of a hole and I'm going to have to live with it? Any tips, tricks, hints, etc will be greatly appreciated! Ryan |
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Re: tailstock Cam lock kit and F/O/R switch change
Ellis, I never thought of using a ring spanner,good idea.No work to do with your method. mike
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Re: tailstock Cam lock kit and F/O/R switch change
I have the kit while the install could be a little fiddly...to a point of annoying the result is great I also have drilled and tapped the 1/2" hole to a 1/2" NPT to accept brass insert so the shaft of the cam can ride on wider bushing type of a hole...worked for me. no miss-alignment听was听experienced听although I do take the听tail-stock听on and off听frequently听
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On Sat, Feb 2, 2013 at 10:52 PM, michael kolchins <kwoodhands@...> wrote:
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Re: tailstock Cam lock kit and F/O/R switch change
--- On Sun, 2/3/13, MERTON B BAKER wrote:
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Re: Horsepower Resistor
--- On Sun, 2/3/13, MERTON B BAKER wrote:
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Re: Horsepower Resistor
MERTON B BAKER
Surely there are radio supply stores in Australia? I know it's vast &
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populated mostly around the edges, but I would think that asking around would turn up a solution. Mert -----Original Message-----
From: 7x12minilathe@... [mailto:7x12minilathe@...]On Behalf Of Den Sent: Sunday, February 03, 2013 4:40 AM To: 7x12minilathe@... Subject: [7x12minilathe] Horsepower Resistor I am trying to by a .025 plugin horsepower resistor for a KBCL-240D board.I found some on US ebay for $5 but postage to Australia is $26. Is there some place that sells these with reasonable postage to Australia. I have probably missed the obvious. Cheers and thanks for your help. ------------------------------------ Yahoo! Groups Links |
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Re: (unknown)
MERTON B BAKER
锘�
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Yep, & we'll need telepathic powers to figure
out what.
�
Mert
�
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Re: tailstock Cam lock kit and F/O/R switch change
MERTON B BAKER
Swapping switches is a simple soldering job if you
know how to work on circuit boards.� The TS camlocks營 made for my 7x
lathes work very well, and I'm sure the LMS ones will, too.� LMS is a very
reliable bunch.
�
Mert
�
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Re: Horsepower Resistor
I am trying to by a .025 plugin horsepower resistor for a KBCL-240Dboard.I found some on US ebay for $5 but postage to Australia is $26. Just unsolder the old one from the board, Jaycar etc will sell you a new resistor (5W IIRC) for under 50 cents. Jaycar won't have the 0.025 ohm one, 0.022 will be their closest (5% tolerance). Farnell or RS will sell you a 1% or 2% version if you really need it. (I have my doubts they're 1% ones anyway.) Tony |
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Re: Newb question about 1/8" cutting tools
MERTON B BAKER
I was lucky that way, having taken Machine tool Lab at tufts in order to
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avoid flunking Math 2, and the first thing taught there was "How to grind your own lathe toolbits." We were all given a #" long piece of 3/8" sq HRS, & told to grind the same shape on each end as was shown in prints in the textbook. With that accomplished, we were given a grade, (I got A) and a 1/4" HSS tool blank, told to make a real lathe tool, and never to complain if it didn't cut well when we were using the lathes. I still have mine, and used the same teaching method when, long afterward I was given the metal shop class in the HS where I was teaching Physics, the regular shop teacher having quit. Toolbit grinding is a basic skill for making things on engine lathes like the 7xs. The size for which they are best adapted is the 8mm, or 5/16" one. While it is true that ready formed toolbits are available, they cost 5-10 times what the blanks do, and money is useful for many other things. Those with an understanding of spatial relations plus a good 6" grinder can easily pick up the skill to grind toolbits, and I have taught many, many others, who lacked this talent, to be skilled toolbit grinders. That, however, is another story, & "Mert's toolbit grinding course, with text & visual aids" is available off list. Fair warning, it is not free. I'm below the poverty line, despite having bought all my toys when I wasn't. Mert -----Original Message-----
From: 7x12minilathe@... [mailto:7x12minilathe@...]On Behalf Of cptwinderatgmaildotcom Sent: Saturday, February 02, 2013 7:17 PM To: 7x12minilathe@... Subject: [7x12minilathe] Newb question about 1/8" cutting tools When I purchased my lathe, I also purchased a few sets of cutting tools: The first ones, the carbide, are completely junk. None of the angles are correct. It is almost like the carbide was brazed on upside down. I have had decent luck with the HSS cutters in the second set. However, they are so small 1/8", you have to use the holders. The holders cause the cutter tip to be a significant distance from the tool post decreasing rigidity. Does anyone else use the tinny cutters and if so what holders do you use? Thanks, Jeremy ------------------------------------ Yahoo! Groups Links |
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Re: Horsepower Resistor
I'm reasonably familiar with KB's website, Den, having used it to find UK distributors.
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If all else fails, you could make one up yourself. Ceramic cased, 0.1 ohm 10 watt wirewound resistors seem pretty readily available, and four of those in parallel would give you 0.025 ohms. They would handle 40W, which is probably an unecessarily high rating for the job, but there's no harm in that. Andy --- In 7x12minilathe@..., Den Strods wrote:
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Re: Horsepower Resistor
The "dealer finder" on the KB Electronics website shows a single distributor in Australia:
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Country/Area: Australia City: Seven Hills, NSW Name: ABB Australia Pty Limited Phone: 02-9674-5455 Fax: 02-9674-2495 E-mail: sales.au@... Web Site: www.Baldor.com.au Product Line(s): AC & DC Drives Stocking: This is a stocking distributor Andy --- In 7x12minilathe@..., "Den" wrote:
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maschwiebert