anyone converted a Sherline / desktop lathe/mill to CNC ?

pogo wrote:


Unless it's a real crap drill press, it will be about as "accurate" as the typical desktop mill. In fact, a mill is just a drill press with some refinements. "Accuracy" isn't always one of those refinements!
For under $100 you can retrofit a Harbor Freight bench drill press to work as a just-passable poor-person's mill. It'll be good enough as a learning tool. You need a basic XY slide, which you will bolt to the base of the drill press. Harbor Freight sells one or two...get the better one, or opt for a model that doesn't exhibit the backlash as theirs do. Try to find a collet holder for the chuck, and invest in a couple of real milling bits. Drill bits are too long and too flexible. You'd be surprised what you can put make after a bit of practice. Start first with some softer materials.
I'm finding that the most fun I am

Absolutely, but as I mentioned CNC is in many ways harder to master than manual machining. I think you're on the right track if you look for a CNC-ready machine, then make that plunge after having built a few miniature steam engines with the thing. <g>
-- Gordon
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"accurate" as

with
refinements!
Wow - I didn't realize that. The inaccuracy I experience could well be from my lack of skills in this department. Mostly, I find that the drill bits wander a little from where I mark to begin the drilling.
The drill press I have is a $100 Craftsman.

press to

as a

the
I keep thinking this may be the best way to go, too. I bought a X-Y machinists vise and although it looks good and well built, the movement on it is less than smooth. Got if off eBay so I was prepared for the get-what-you-pay-for effect. No big surprise. I'm sure a real X-Y slide would be better anyway since it would provide more ways to clamp something down.

as
in a

flexible.
Start
I just read what you wrote about drill bits being flexible! Duhh! I think that is a large part of my problem. I am definitely going to read up on this some more and see what I come with. Perhaps by that time my "fever" will have gone down some and I will listen more to my bank account than my "fever for a new toy"! :-)
Thanks Gordon! Always good advice from you. James C. Deen
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pogo wrote:

Absolutely. This is from a combination of having the wrong point on the bit, no starting punch mark, and perhaps even the surface shape of the part (rounds tend to cause more walking around that flats).
There are a couple books you may want to look into, and most are older so they should be at the library. One that's pretty good for beginners is is Home Machinist's Handbook (Briney). It's about half pictures and half text, and is not bad as a beginner's book. The other is Joe Martin's Tabletop Machining. As he owns Sherline it's Sherline-centric, but much of the information applies to most any tabletop machine you might have. I found he jumps around a bit, but just about all the info you'd want is in there.

Check out Reid Tool & Supply for some decent end milling bits, in different sizes, shank lengths, and point styles. For practice you'll want 2-flute square end. Diameter shouldn't be less than 1/8"; 3/16" is even better for playing around.
Of course, eye protection is the most important tool you have in your garage. It takes all of a split second for some aluminum sliver to get into your eye, but several hours at the hospital to remove it before it scratches the hell out of your cornea.
-- Gordon
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older
beginners
pictures and

Sherline-centric,
you
info
I just got Martin's book in the mail from Amazon. It looks like one I will read & flip through, then read and flip thru some more when I *really* understand what he is talking about. Kinda like yours! :)

you'll
3/16" is

Will do. Thanks for the tip on Reid Tool & Supply.

your
to get

before it

This is one thing I *do* know. With age/experience has come the realization that even mundane chores can throw a sliver of something bad into your eyes. The scariest and the one that really made me realize this was when I was tinning the end of wire with some solder one day - pressing it against the wire - the solder slipped off & the wire flung a tiny bit right into the corner of my eye! It scared me so much I'm not even sure I felt the heat. So now I always wear glasses for that and a few other things I used to skip protection for.
And of course, I have verified for myself that one needs to clamp down metal work when using ANY kind of saw or high speed device - not just hold it by hand. There is a piece of metal that is still lost in my office/shop - it went to it's hiding place at high speed not long ago. Whew! I may add a Kevlar vest to my safety tools!
Gotta get some shuteye ... JCD
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Hi,

The real problem with trying to do this, is that most drill presses hold the chuck into the spindle using a taper. Lateral (i.e. sideways) pressure will cause the taper to loosen, and now you have a spinning chuck with an endmill on it, potentially flying around.
In order to safely use a drill press as a mill, you really need a drawbolt or something similar to secure the chuck to the spindle.
Obviously, if you're using a drill mill, then it will have the requisite drawbolt, but a regular drill press doesn't
Dave Hylands
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The machines are small but you can modify them to machine a bigger foot print. Here is a mod I did to increase the table travel of the mill and also to allow for a lathe conversion.
http://www.imaginerobots.com/cnc_mill_stock/source/cnc_mil_main.asp
DT
pogo wrote:

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snipped-for-privacy@aol.com wrote:

I've spent a life time doing woodworking and have quite a collection of woodworking equipment but I've never learned much of anything about metal working. My metal working skills and knowledge are mostly limited to what you can do with a drill press, grinder, hacksaw, and hammer. I've always wanted to learn welding (all types) as well as skills like machining. All this talk about these little Sherline machines is making we want to go out and get one as a way to get into this.
From all the pictures (and a lack of experience with this stuff in general), I'm having a little trouble understanding what the real scale of these machines are. Just how large of a piece can you mill with these machines (without the help of machine modifications)? For example, if you wanted to mill something that started out as a cube, how large of a cube could it work with? Is it only a few inches, or is it more like a foot or more square?
And for precision and accuracy, are machines in the price range of the Sherline in the same accuracy range as higher end larger machines? Is the main difference only size and power? Or is there an important difference in it's precision?
I love tools and the thought of being able to machine custom pieces for my robotics projects just sounds like it would be a blast. And a machine like the Sherline would be very affordable for me. But I just want to get a little better feel for what it can really do and what it can't do.
--
Curt Welch http://CurtWelch.Com /
snipped-for-privacy@kcwc.com http://NewsReader.Com /
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Curt Welch wrote:

The main picture at the Sherline site (http://www.sherline.com /) gives you a good idea of the scale. Those are standard-size books. You can see the lathe is limited to a block no more than a few inches square by whatever the bed length is (it comes in a couple of lengths). The mill is limited to inches as well.
They have a page on instructions for their machines, which specifically talk about the size limitations.
-- Gordon
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Curt Welch wrote:

I have used both big and small machines. I don't think the accuracy is much different, but acheiving that accuracy requires more skill and patience on a small machine. But it is still much better to start with a small machine, because it will help you develop that skill. A Sherline is small enough for you to feel the vibrations as you cut into a piece of metal. You are close enough to smell an overheating bit. You will get a good intuitive feeling for how to cut different materials. You will be able to tell when a bit is too dull just by listening to it cut. You will become a better machinist than someone who has only used big machines.
Shortly after you buy the mill, you will find you also need a rotary table. So you may want to go ahead and buy them together and save on shipping.
Some other advice: Don't think of these as just metalworking tools, they are also great for plastic. When I need to machine a robot part, I probably use acrylic or acetal (Delrin) 80% of the time. Acteal is very easy to machine, and is quite rigid and strong, but not as cheap as acrylic.
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of the

machines? Is the

difference
Plastic is a large part of what I want to do with a min-mill/lathe, too.
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pogo wrote:

Whole new world. Plastics requires very specific adjustment of spindle and feed speeds, or else the plastic gets overheated, gumming up the tooling, releasing toxic fumes (if the plastic melts or burns), and producing extremely out-of-tolerance parts because of expansion. In fact, plastic expands quite a bit even if you're careful, so you need to take this into consideration when producing the part. The expansion changes depending on the type of plastic, amount of cutting, and its cubic size.
In some ways, working with plastic is harder than aluminum -- first hand experience here. Learn on one of the softer alum alloys first.
-- Gordon
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Bob wrote:

Fur lurkers: Acetal really stinks if you overheat it (it's the formaldehyde releasing), so make sure the bit is sharp.
For Bob: I personally like high density polyethylene. Cuts and mills like butta, and doesn't release so much smelly stuff. About as durable as acetal, but maybe not as dimenstionally stable. You can buy a cheap kitchen cutting board to play with it before purchasing a larger sheet from the local plastics outfit.
-- Gordon
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Gordon,
Where would you go looking for surplus plastics and metals for robotics?
Thanks
TMT Gordon McComb wrote:

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Too_Many_Tools wrote:

Because most of the work I do now is for resale wioth Budget Robotics, I don't use surplus. For plastics, it's far better to buy new sheets anyway, as you get a consistent quality, and the price (for the kinds of materials I use, such as PVC, HDPE, and ABS) is reasonable. Most areas have a plastics distributor that offer these by the sheet. (My CNC router also needs sheets in specific sizes, so I can't use odd cutoffs.)
For metal I used to buy the wrought iron from welding outfits. It's pretty cheap. The aluminum channel stock I've always gotten either from the hardware/home improvement store, or for as-milled alloy a local metal surplus outfit. Down in San Diego we have K Street Surplus, plus a bunch of others. We also have a major Navy shipbuilding presence, so you can imagine surplus metal is not too far away... <g>
-- Gordon
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