Suggestions for small mill/jig borer?

pete said:

Going by what River1024 posted, he's wanting a small and meant for the task light duty jig bore class of machine. Some of the brands he mentioned were built with a special and very high accuracy fixed rotary table as part of the table. These light jig borers get built with very rigid or fixed heads, extreme accuracy spindles, bearings and spindle tapers. Lead screws and nuts are at least an order of magnitude better than my BP clone without my dro. The machines exact alignments were hand scraped to that jig borer designation for accuracy. Some were even made with built in compensation for the machines dials and the known but very slight feed nut and screw pitch inaccuracies the factory tested for and knew by exactly how much each machine varied from true position over the full X,Y travels. There simply isn't any mill being produced today that comes even close to what one of these machines were capable of as long as one can be found that's still in decent condition. There small size does not mean less accuracy, and they were just as capable as any of the full sized jig bores.

Click to expand...

Mike Henry said:

You might keep an eye out for a Linley Jig Borer. They used to be popular amongst hobby metal workers but are not mentioned much anymore and are pretty rare. If you go looking, try to get one with the power downfeed and all the collets, which might have been custom-made for the machine. Prices used to be $1500-$3000 depending on location, condition, and accesories.

http://vintagemachinery.org/mfgindex/detail.aspx?id=9381&tab=3

If a vintage (small) mill is a better fit for you, Clausing sold the 8520 and 8530 vertical knee mills that are fairly easy to find and Rockwell made a slightly larger knee mill that some prefer. Both are 700-1,000 lbs and documents for either can be found on the above site. I owned an 8520 and used it happily for a number of years until it was sold to make room for a new tool. It brought a little over $3k, but was in excellent condition with a 3-in Kurt vise, DRO, power feed and full set of MT-2 collets.

https://lathes.co.uk/#gsc.tab=0 also has a lot of info on all sorts of machine tools in a format that some find easier to explore.

Click to expand...

pete said:

I bought my 3/4 sized BP clone from Penn tools in New Jersey and shipped it over 3,000 miles to western Canada simply because at the time, Penn Tools were the only ones importing what I needed for size and overall weight from Taiwan. I also spent over 10 years looking for a reasonably priced South Bend 7" shaper within a few hundred miles. That never happened. I finally made up my mind that if I was ever going to get one I was going to have to change my requirements. I probably paid a couple hundred too much at the time, and it took a 15 hr round trip to get mine, but in hind sight I'm happy I finally understood what it was going to take and acted on that or I'd still be looking.

I'd say you already have about all the known and better machines on your list and I doubt I can think of any you might have missed. And as you already know, all of them would be quite rare to find in the U.S. If it were me, find a complete and excellent condition machine including collets (especially so for those BCA's) anywhere you can which is likely to be in Europe, then send multiple emails to lesser known freight companies using a Google search around the general location of that machine for both crating and shipping. DON'T even talk to the big names in the fast freight and shipping business like DHL, UPS, FedEx ect. All of them will always cost the most by a very large percentage. Who do you think pays for all there advertising for them to be well known? And get at least 1/2 a dozen freight quotes from different companies. I've seen as much as 300% more from the highest cost companies verses the lower cost. A small heavy piece of freight like this would almost for sure be put out for bid by the big freight companies and picked up by one of the more local freight companies anyway. Then those big companies take most of the profit simply for shuffling some paper work around. A bit of Google searching and some emails can easily save you some big bucks. If you want fast, easy and convenient it's going to cost a lot. Do a bit of the work yourself and you'll get a much more reasonable price.

Click to expand...

river1024 said:

I do thank you for the suggestions, I had not looked at Clausing. It may be something to look into for the future for larger stuff. Though, while it’s still small compared to standard mills, I should add I am on the third floor of an apartment. And no garage. Anything above 500lbs is just going to be impossible. And even 500 is pushing it.

Click to expand...

pete said:

Yes clocks and watches were made by hand on some pretty crude and rudimentary equipment by some highly experienced craftsmen 100's of years ago. I'd stress that word experienced since it fills in for a lot of the deficiencies and lack of precision in the equipment that was available at the time. What worked then can be just as true today. You still need that knowledge and the experience though. In general, I'd say there's a real lack of understanding about the basics of machine tool alignments by most at the more hobby level. Buying something like a small but proper jig borer level machine, then all that's already taken care of as long as it's not too highly worn. It's part of the high cost and what these machines originally sold for when they were new. I have a fairly extensive collection of older model engineer magazines, in the early 1960's one of those bare BCA's without any tooling were selling for approximately 3 times what a then new Myford Super 7 was priced at.

But even with something like a machine built to those jig borer specifications, a good craftsman would still check what they bought to find where the accuracy limits of any machine tool might be. All the experience and knowledge in the world still can't allow for compensation on any machine tool if you don't know where any inaccuracies are or how much or if any compensation might be needed once those part accuracy levels go high enough. Using that exact same method is in fact how we got to the very best and most accurate machine tools we have available today. At some point highly experienced machinists were making manual corrections to then build more accurate machines than what they were being machined and / or ground on. After that, then more knowledge and experienced were used to hand scrape them to even far higher levels of accuracy.

For almost all of us, what were buying for the smaller bench top sized machines will usually be good enough at our more hobby level, until it isn't. High accuracy work is obviously a bit different. There's hundreds if not thousands of posts on various forums mentioning lathe leveling or tramming a mill vise and head in. While obviously important, what about the rest of the machine? For example how many have ever checked just how true there mill tables Y axis is to it's X axis. Most seem to assume there perfect, they most definitely aren't unless it's by a lucky accident. Moore Tools in there book Foundations of Mechanical Accuracy very aptly illustrate that for any single machine tool slide, there's up to 6 possible directions of inaccuracy's that can be present, or even various combinations of some or all of them. A massive learning step for myself about those machine tool alignments and how to check them was finding this PDF. https://pearl-hifi.com/06_Lit_Archi...s/Schlesinger_Georg/Testing_Machine_Tools.pdf I suspect a large amount in that PDF was used as the methods contained in the Connelly book Machine Tool Reconditioning. And without question it's methods have been used by every machine tool manufacturer world wide since it was first written in the 1930's and still are today. My last lathes certificate of accuracy was certainly based on those exact same Schlesinger's test methods.

I'd say the actual differences between something like an off shore mini mill and one of those Houser's, BCA's, Bolley's etc might be roughly comparable to the difference between a $200 off shore drill press and my Bridgeport clone. But with that test information, maybe some adjustments, shimming etc, plus already knowing where the limits of accuracy are. Then that extra knowledge and experience can wring a lot more out of these machines than they were ever really designed to do. I'm not suggesting that any of those light duty off shore machines will ever come close to what the OP is looking for, only that they can be much better than what comes out of the shipping crate. It's then up to the user to say if that's good enough or not.

Click to expand...

river1024 said:

Thank you for the information, and the PDF. I had not considered condition. Well, of course, I did! but, probably not as much as I should have. I got my lathe used, but with only an hour or two of runtime. Still, it is probably about as perfect as I can get when it comes to lathes for watchmaking. As far as quality control. (Michael Chung CZ50).

I know the cheap machines *can be* capable. Because I know of people who have made a watch using a Sherline lathe and mill. But, that is where tons of previous experience / knowledge, and modifications and setups come into play. Things that I, as a beginner, just don't know about general machining.
I am absolutely not against learning. I would love to know everything there is to know. However, at the moment, I think getting a good machine will eliminate a lot of the things that could go wrong by having machine issues. I just know how to measure, work with tolerances, read technical documents, etc.

I feel like I can maintain a good machine. But I cannot compensate to make a bad machine better. Without more knowledge than I have now.

I will be using a few older methods that watchmakers used to use though. For example, I have a depthing tool and uprighting tool I will rely on.
If I cannot sequentally and accurately drill all the location holes, I will go step by step for each one, and use the depthing tool, and bore them out on the lathe with centering scope.

Side note, thoughts on precision matthews mills?

Click to expand...