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Advice Sought for New User
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Hi,
I am thinking about bying a Mini-Lath (like the one shown on mini-lathe.com). Among many reasons, the main reason is to make a part that is essentially a tube (aluminum alloy 6061) that has an outside diameter of 0.437 inches and a wall thickness of 0.016 inches. I want to be able to flare the end when I'm finished, so my first question is, by milling the aluminum on a mini-lathe, will that ruin the temper of the alloy such that it can't be flared afterward? My second question is this: I also want to start from a stock of outside diameter of 0.625 inches, reason being that I want one end (not to be flared) to be left with a "bead" of a diameter 0.625 inches. Can these lathes do this kind of thing, that is, make tube that one would get as if you had a machine that form an "outward rolled end"? |
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Hi,
I'm no expert on 6061 alloy but I doubt you'll be heating it substatntially. Maybe a little work hardening. I'm more concerned that you seem to be planning to make your own thin walled tubing with a 16 thou wall thickness. You didn't say how long. If it's of any length I think it will be difficult. Even a centimetre would take some care at that wall thickness. Are you committed to those dimensions and concepts? I assume you need more than one if you're looking to buy a lathe to do it. John --- In 7x12minilathe@..., "nicipi" <nicipi@...> wrote: part that is essentially a tube (aluminum alloy 6061) that has anoutside diameter of 0.437 inches and a wall thickness of 0.016 inches. Iwant to be able to flare the end when I'm finished, so my firstquestion is, by milling the aluminum on a mini-lathe, will that ruin the temperof the alloy such that it can't be flared afterward? My secondquestion is this: I also want to start from a stock of outside diameter of0.625 inches, reason being that I want one end (not to be flared) to beleft with a "bead" of a diameter 0.625 inches. Can these lathes dothis kind of thing, that is, make tube that one would get as if you had amachine that form an "outward rolled end"? |
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Yes, this is essentially a thin wall tube. But I am after 1 inch
lengths in the end. And I need many - like 100. The dimensions are very important, which is why I'm having trouble finding the tubing that I need (McmasterCar, etc.) So my take from your concern is the 0.016 inch is not within the precision of a mini-lathe, or is not a safe operation? Does having a short length like 1 inch seem more reasonable to achieve this objective? |
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--- In 7x12minilathe@..., "nicipi" <nicipi@...> wrote:
part that is essentially a tube (aluminum alloy 6061) that has an outsidewant to be able to flare the end when I'm finished, so my first questionis, by milling the aluminum on a mini-lathe, will that ruin the temperof the alloy such that it can't be flared afterward? My secondquestion is this: I also want to start from a stock of outside diameter of0.625 inches, reason being that I want one end (not to be flared) to beleft with a "bead" of a diameter 0.625 inches. Can these lathes do thiskind of thing, that is, make tube that one would get as if you had amachine that form an "outward rolled end"?Hi, I think the only way of doing this is to first make a steel mandrel of diameter slightly less than the id of the tube. The mandrel should be made with a flange at one end and it should be accurately centre drilled at the flanged end. The mandrel should be longer than the tube you want to make. Once this is made then mount the the 0.625 bar in the 3 jaw chuck. If it is long (more than 3 times the diameter) you will need to used a fixed steady at the far end. Now centre drill and then drill to the required internal diameter. Remove the steady and insert the mandrel. Support the mandrel with a live centre in the tailstock. Now you can turn down the OD to the required diameter taking light cuts as the wall thickness decreases. Using a mandrel in this way ensures that the tube will be well supported during machining. With regard to the temper of the alloy this should not change during the machining operation but the alloy may work harden making flaring difficult. Tyhe easiest way round this, if it is a problem, is to anneal the tube after machining. To do this just smear the tube with soap and heat it gently with a blow torch until the soap blackens. Then qunch in water. The material should be very soft after the treatment and flaring should be easy. Kind regards Mike Kingsley, UK |
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Hi again Nicipi (is that your preferred handle?),
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It's probably within the capabilities of these machines. More readily so at just 1" length. You'll want a reasonably rigid toolpost so I suggest you look at the lapping job that people do to these Asian machines to improve that area. I'd certainly use a mandrel as Mike suggested. Depending on your tolerances and surface finish needs you may need to use a reamer but that seems tedious for 100 items. They aren't cheap either but at least it's not a 1-off. OTOH, you may be happy with just drilled and bored. At that length you may be able to avoid needing the tailstock and centres. You're inside the usual 3 diameters rule of thumb BUT you're going pretty thin walled and can't afford too much flex. You'll soon figure out if the extra messing about with the T/S is worth it. Something to note. 3-jaw chucks are not the most precise. Their design is necessarily a compromise. Re-read Mike's suggested steps and you will notice that the job is not removed from the chuck from beginning to end. This negates the innacuracies of a 3-jaw. Your job will be created true to spindle axis and remain that way - unless you're silly enough to remove it and subsequently try to re-chuck it. You won't get it back to the same axis again. The alternative is to use a 4-jaw chuck and set up with a dial gauge. For your application I'd try to stay with the 3-jaw. It's so much simpler to set up. I'm just making sure you're aware of some of the hidden finnesse in Mike's method. With planning, you should be able to nut out a 3-jaw method along the lines Mike suggested. John --- In 7x12minilathe@..., "nicipi" <nicipi@...> wrote:
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Mike Payson
Would there be any benefit of a 6-jaw chuck in an application like this?
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) On 3/30/07, born4something <ajs@...> wrote:
Hi again Nicipi (is that your preferred handle?), |
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G'day nicipi.
You have some sound adice from Mike & John. The limitation to what you want to do will be the strength of the material and your skill. I take it by your question that you may not have used a lathe before. Having a specific project is a great excuse for increasing your retinue of tools, I should know, my shop is full of them! If you have this project as an excuse to buy a lathe which you've always wanted, then go ahead. Be prepared to spend time gaining and improving your skill, this is the best part, very good for your self esteem. IMHO for every hour spent improving the lathe to get better outcomes, 10 hours will be spent improving your personal skills. The scrap bucket is a great invention! The problems you will face with what you propose include: Distortion of the 16thou walls of the tube as you take the final cut, the tube wall may even tear. If made from tube then distortion in the 3 jaw chuck. Mike's proposal with the mandrell will help over come these problems. For me I would make the part out of bar and drill and bore the hole to depth. Insert a mandell in the outer end to support the work on the tailstock then turn down to the diamemters you require. You will have to experiment; it may be better turning the 0.625" diameter at the TS end. Also doing the reduction of diameter to the 16thou wall thichness may be better as one full depth cut with a sery slow feed rate. TOLERANCE: No! I'm not talking about putting up with my comments! No machined part is every exactly the same dimension, CNC stuff may be close, but never identical. You have given us dimensions but have not said what the tolerances are. That is, the range of internal diameter, wall thickness, collar diameter and lengths. Be warned. IMHO, as a newbie, you will be lucky to get within 3thou on any dimension. By now you will have either decided this is not for you or become excited at the prospect of increasing the range of your skills. As an alternative I am sure there are a number of skilled minilathe owners with some time to spend to make or try to make these parts for you for some recompence. As I say. One good turn deserves another. Regards, Ian |
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It's well within the lathe's capabilities. The tricky part is going
to be working with the thin wall without tearing or distorting the piece. Since it's only 1" long, I'd make it in one chucking, parting the finished piece off of a length of stock. Rather than flaring it after it's made into a tube, consider machining the flare while it's made into tubing. 6 jaw chucks are ideal for working thin walled tubular pieces, the clamping force is distributed over more area than with a 3 jaw. For tubular work, collets are also convenient. Since they distribute the clamping forces over even more area, they're better than a jawed chuck. They're also more accurate than most chucks. You can solve the rechucking problem by making an adjustable backplate for the chuck, ideal with a 4" chuck, since you need a separate backplate to mount it. Roy --- In 7x12minilathe@..., "nicipi" <nicipi@...> wrote: part that is essentially a tube (aluminum alloy 6061) that has an outsidewant to be able to flare the end when I'm finished, so my first questionis, by milling the aluminum on a mini-lathe, will that ruin the temperof the alloy such that it can't be flared afterward? My secondquestion is this: I also want to start from a stock of outside diameter of0.625 inches, reason being that I want one end (not to be flared) to beleft with a "bead" of a diameter 0.625 inches. Can these lathes do thiskind of thing, that is, make tube that one would get as if you had amachine that form an "outward rolled end"? |
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First, thanks for all your feedback Mike, John, Ian and Mike - you
guys have added a lot to my sense of what's involved in this endeavor. I should at least clarify my tolerances. The wall thickness can actually be anywhere between 16thou and 32thou, and every one that I make can be in that range (don't all need to be identical); the only restriction here is that it still be flarable. Also, the thickness should be relative to the 0.437" outer diameter of the main part of the tube (the 0.437" can be plus/minus 5thou or maybe even 10thou). It is important that the 0.625" "outward rolled-like bead" be clean and rounded (a picture would really help here - I have a photo and a schematic but don't know how to share it with you guys). Otherwise, the surfaces don't need to be perfect, so for example, as John points out, the inside of the tube can be done with just drill/bore (if I'm using the right wording). What I first need to do is make sure I understand the procedural options here. Each of you guys have added something unique to try, and I've been reading your instructions over and over. What's just now becoming a little clearer to me are things like what does the tailstock do, what are the options for supporting the piece, what are centers, etc., and most importantly, what is a mandrel and how is it used (so that I can implement Mike's technique or variant thereof - the mandrel seems to be a key here.) It certainly would be helpful to see one of these machines up close and in action. I even looked on youtube but only one video came up when I searched on "mini-lathe" and it wasn't very enlightening. Nicipi |
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Mike Payson
Hi Nicipi,
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I'm certainly not an expert. I'm only a bit more advanced then you are. It sounds like what you want to do should be well within the capabilities of the lathe. It might take you several tries to get the process down, but the nice thing about doing a bunch of the same part is you have plenty of opportunity to practice. FWIW, you might want to start with some tubing (such as ) instead of rod stock. (Or maybe not, like I said, I'm a newbie too...) Mike On 3/30/07, nicipi <nicipi@...> wrote:
First, thanks for all your feedback Mike, John, Ian and Mike - you |
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G'day Nicipi.
I'm glad you are still with us. Your tolerances seem more generaous than implied by your initial description. Regarding the video/DVD. I am sure links from minilathe.com will find something. I think Frank Hoose has an instructional vidoe. See also minilathe.org.uk ,this guy has some good stuff. Try Googling "mini lathe" and "DVD" or "video". Places like Plough Books and Camden Books have books and I think you will find videos also, they handle international orders well; try eBay also. I look forward to hearing your progress. One good turn deserves another. Regards, Ian your--- In 7x12minilathe@..., "nicipi" <nicipi@...> wrote: be flarable. Also, the thickness should be relative to the 0.437"outer diameter of the main part of the tube (the 0.437" can be plus/minusof the tube can be done with just drill/bore (if I'm using the rightjust now becoming a little clearer to me are things like what does theare centers, etc., and most importantly, what is a mandrel and how isit used (so that I can implement Mike's technique or variant thereof -lathe" and it wasn't very enlightening. |
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Jim
If you are more interested in having the parts you describe instead of learning and playing with a lathe, you might do well to consider www.emachineshop.com. They have a small software program to download that allows you to make a sketch that gets quoted. You can experiment with a variety of manufacturing techniques, materials, quantities, tolerances, etc. to see what each option would cost. You can do all of this before you submit it to them for manufacture. You can also email them about other manufacturing options that you may not be aware of.
As others have said, the learning curve and cost of additional tooling are both fairly steep - worth it, mind you, if that is what you want to do, but otherwise maybe not the best approach. Jim nicipi <nicipi@...> wrote: First, thanks for all your feedback Mike, John, Ian and Mike - you guys have added a lot to my sense of what's involved in this endeavor. I should at least clarify my tolerances. The wall thickness can actually be anywhere between 16thou and 32thou, and every one that I make can be in that range (don't all need to be identical); the only restriction here is that it still be flarable. Also, the thickness should be relative to the 0.437" outer diameter of the main part of the tube (the 0.437" can be plus/minus 5thou or maybe even 10thou). It is important that the 0.625" "outward rolled-like bead" be clean and rounded (a picture would really help here - I have a photo and a schematic but don't know how to share it with you guys). Otherwise, the surfaces don't need to be perfect, so for example, as John points out, the inside of the tube can be done with just drill/bore (if I'm using the right wording). What I first need to do is make sure I understand the procedural options here. Each of you guys have added something unique to try, and I've been reading your instructions over and over. What's just now becoming a little clearer to me are things like what does the tailstock do, what are the options for supporting the piece, what are centers, etc., and most importantly, what is a mandrel and how is it used (so that I can implement Mike's technique or variant thereof - the mandrel seems to be a key here.) It certainly would be helpful to see one of these machines up close and in action. I even looked on youtube but only one video came up when I searched on "mini-lathe" and it wasn't very enlightening. Nicipi |
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