In machining any plastic, it is very important to cut rather than melt the plastic! Use sharp cutting or drilling tools, at slow speed, and avoid heat build up. My impression is that Dremel is a very high rpm cutting tool, and if this is correct, Dremel will probably melt the Delrin, and as you say "gum up the tooling".
Because Delrin has a high crystallinity (for a plastic) it machines better than other plastics, but it is not infinitely forgiving of high rpm cutting tools.
I turned some 7/16" Delrin rod down to 7/32 the other night at about 1200 rpm using a freshly ground HSS bit. That seemed to work fine so maybe it will give you an idea of what sort of speeds will work.
What do you define as major machinery and what sort of budget do you have for tools?
I've never seen or used a Dremel lathe, but suspect that it hass too much runout for much accuracy and the surface finsh won't be too pretty. It also probably won't work very well if you need to turn down some 2" OD Delrin rod.
Maybe I missed an earlier reply from you but did you ever mention mention what sort of accuracy you need and what sort of parts you are trying to make? The answers to those questions would garner much better advice.
As far as what I define as major machinery, that would be anything I can't keep in my room. :-) And as for a budget, what's that? :-)
Since I'll be working with Delrin and stainless steel I have been looking for the necessary tools to accomplish what I want to do. I recently won a Rotabroach on eBay and I think that perhaps I should get a micro-mill next.
Here's a Dremel Lathe:
I've also recently won bunches of Delrin rods on eBay. The largest diameter being .750".
I figured that it was a long shot, but I was looking into possibly making some of the smaller parts I need with the Dremel lathe.
As for accuracy, how do you gauge that? I want to be able to turn down a Delrin rod to 1/4" diamter and use it as a hinge pin in a 1/4" hole that I also drilled in Delrin.
[That seems basically possible to me. I've machined Delrin and it worked pretty well. It's harder to clog up a lathe tool than an endmill (which is what I was using) so I'd rate your chances of success pretty high. It doesn't sound like your tolerances are too tight, but a 1/4" rod would have a hard time fitting in a 1/4" hole if everything was exact. You either need to make the rod a tiny bit smaller or the hole a little bigger for it to function as a hinge. If the hole is drilled, it can be made more round by reaming, and the diameter will be more accurate; drilled holes are somewhat triangular.]
Some pretty large tools can fit in a room but it sounds like you are limiting yourself to the smaller benchtop models for things like a lathe and mill.
A budget is what you can afford to spend and it sounds like you don't have much money available. In that case, do your homework and get the best you can afford.
The question was asked because there is no pint in suggestion a $5,000 answer if you only have $5 to spend.
A mini-mill might be more suitable for Rotabroaches unless they are really small. Especially if you plan to work in SS. Make sure that whatever you buy is big enough to take the larger tooling you expect to use and has enough work envelope for the projects you expect to work on.
That looks essentially useless for machining to me unless you are planning to work with Balsa wood and don't really care about the appearance of your parts. There's no compound, no cross slide, no threading capability, and no chuck. It's a non-starter for SS.
Accuracy is usually indicated as a plus or minus dimension; i.e. 0.250" diameter +/- 0.002", though there are lots of other ways to express it. You need to specify the accuracy of a part in some form or fashion in order to determine what tools and techniqes are appropriate for the job at hand. If you want a clearance hole for a 1/4" bolt you can get by with using the next larger size drill bit from your set (say, 9/32"). If you want a hole into which you will press fit a 0.250 rod you will need to ensure that the hole is smaller than the rod by just a few 10 thousandths of an inch. Measuring that accurately can be a bit tricky. For hobby work, one usually just makes the parts to fit.
The Dremel lathe you are looking at on Ebay is made for turning wood. It might not be the tool you are looking for. There are other small lathes and mills that would do what you require. Sherline and Prazi are two names that come to mind.
As others have mentioned you might also want to consider Sherline or Taig. I have a Sherline lathe and mill and both of those will do accurate work on most materials (including SS) but suffer from relatively small work envelopes and the need to make fairly modest cuts. The lathe is limited to
3" diameter work (6" with riser blocks) and the mill has travels of 3"x9"x6" (X-Y-Z). Delrin should be easy to work with either but you will probably find that SS is a bit more time consuming when using end mills or fly cutters. I found that depth of cut was limited to something under 0.025" in the more difficult to machine materials.
For gear cutting you are probably going to need a dividing head. It may be hard to find one sized for the MicroMark-sized mills but Sherline has one.