I had one year of shop class prior to the engineering college, and I was actually quite skilled at using a lathe at that time. However that was 24 years ago.
The two most difficult things as far as I remember was turning correct fits for bearings, and to cut threads on the lathe. Not the type where you use a tap or a die, but grinding the tool bit and adjusting it all and then lead the lead screw take care of the pitch.
Searching for an appropriate challenge, I ended up reading about the Stanley # 20 compass planes.
According to Patrick Leach's excellent pages on Stanley planes , the # 20 often has the original knurled locking screw replaced. So making a new one of those might be helpful to someone out there sitting with a recently acquired #20 missing that screw.
However excellent Leach's page is he doesn't reveal the thread of this screw, but I managed to find that information on a British tool forum.
The screw was apparently of the much under appreciated UNS standard, namely a UNS #10-28.
This just kept getting better and better!
A rare screw with a sort of obsolete and no longer used standard.
I googled the Standard and found the necessary information about the thread, so I could proceed to the workshop.
We have a very limited supply of tools for the lathe out here, and off course the most important thing for thread cutting was missing: A thread cutting tool.
After scouring the shop I found some old parts from a diesel injection valve, and those parts are made out of hardened steel. So I ground one of them into a 60 degree tip so I had something to use.
A piece of brass was turned to the desired dimensions, and then it was literally time to change gears.
Most simpler types of lathes that have a thread cutting capability will need to have the gears changed in order to switch from metric to module to imperial threads etc.
There are some small tables on the face of the lathe that will tell you how the correct configuration is, and once you have got that right, you just need to correctly position two handles and two knobs - and you are ready to go.
On the first attempt I managed to mess up the thread. But on the second attempt it came out all right. I think it could have been a bit more crisp, but without a proper thread cutting tool and an thread cutting tool position gauge, I just had to sort of eyeball it.
After the threading, I inverted the cutting tool, and used one of the gears as a dividing head, so I could make some knurling lookalike.
Due to my goodhearted nature, I have decided to offer this screw for free - to the first Alicante based American woodworking blogger that comments on this blog.
UNS #10-28
Gear setup for metric (42:120:42)
Gear setup for imperial 28 TPI, (32:120/127:48)
Stanley #20 locking screw.
I have just literally just finished stripping the rust and paint from a #20I just bought this week.And yes, the locking screw doesn’t fit, it looks suspiciously like a lever cap screw from a modern (English) #78. Once I finish refinishing it, I have three options. The first is to cannabilize something from my collection of #45 parts and general parts from #4 &5 planes. The second is to fashion some kind of locking collar to clamp on the adjusting bolt. The third is the worst option, to drill out and re thread the casting to accept a common 1/4” 20 tpi bolt.
ReplyDeleteAnyways, enjoy your blogs and envy your machining skills
Edward Suter
Vancouver Canada
Hi Edward
DeleteThanks for the nice comment.
I hope that the thread inside the hole hasn't been damaged by someone inserting the wrong thread.
It is fairly easy to mistake an M5 screw for the #10-28. So maybe that is what has happened.
I can try to make a locking screw for you tonight, but I can't guarantee that it will fit. Technically I don't know if this one will fit either since i haven't got the plane to test it on. But I am pretty sure that it will work.
I just tried to send you a message via Google Plus, but I think I screwed up..
Best regards
Jonas
Wow, reconstructive industrial archaeology at sea! I was ready to read that you scavenged the brass from a broken part of the ship. But can you be certain of the fit without having inserted these new threads into a corresponding item? And I want to thank you for citing the British website.
ReplyDeleteHi Mitchell
DeleteI didn't have to do any scavenging this time, because we did happen to have a piece of brass in the workshop that could be used.
I can't be completely certain that the screw will fit, but if it is anything I think it might be a bit on the loose side.
The British forum was new to me, so I figured that it didn't hurt to link to it, and after all the guy who was so kind to share the information about the correct thread deserves to be acknowledged.
Brgds
Jonas
I have no doubt the diameter and pitch are correct as per standard. The depth of cut might give a tight or a loose fit.
ReplyDeleteThe "Alicante based American woodworking blogger" we all know, will tell us.
I guess you put the lathe back in metric to avoid surprises.
Sylvain
Hi Sylvain.
DeleteI think that it might be a bit on the loose side, but I decided that that was preferable to a tight fit.
We will have to wait for the result until I get home and can mail the screw to the Alicante based woodworker, to hear his verdict about the fit :-)
I actually think I'll just keep the lathe with the current gear setup.
I was the one who changed the gears last time too, and no one besides me ever uses it for cutting threads.
Actually very few people beside me use the lathe at all.
Brgds
Jonas
Me! Me!
ReplyDeleteHaha! I'm amazed, Jonas. We just spoke about this yesterday. I'm still making mental plans (couch building) how to rehab this old plane.
It looks wonderful, and I'm sure it will work perfectly.
CONGRATULATIONS!!
DeleteYou are the first American Alicante based woodworker to comment on this post :-)
I'll send it to you once I home in about three weeks time. So you will have ample time to do a clean up of the plane and fabricate a box for it.
Brgds
Jonas
Jonas
ReplyDeleteVery cool! I am on the verge of getting my lathe up and running after a few years in mothballs in the barn basement. Stay tuned.
DCW
PS I really think you should move to the mountains of Virginia.
Hi Don
DeleteThanks for the nice comment.
I think I ought to move to Virginia as well, but I still need to convince the rest of the family that it is a good idea.
I have long toyed with the idea of turning a large wooden screw for a leg vice on my metal working lathe at home.
But I have sort of promised myself that next home period will be about finishing some "honey do" projects that has lingered for far too long - such as whitewashing the stable, completing the concrete casting of the floor int he stable (one small corner missing), make firewood ready for the winter etc. etc. As a mountain man you surely know that all those things that should be ready for the winter months :-)
Best regards
Jonas
Hi Jonas,
ReplyDeletemy #20 doesn't need a screw but I have always been interested in how to use a lathe. Be it for making screws or any other part in metal I might need.
Hi Ralph.
DeleteI'm glad that your don't need a screw, because I had to do a couple of tests before sorting it out on the screw to Brian.
I eventually found out that there was more slack in the feed mechanism than I anticipated, and given that this pitch is so fine there isn't room for a lot of error.
Even when I tried my best to hold on to the locking lever, it would still eventually slip maybe 1/64" But since the pitch is 28 TPI, it is close enough to make sort of an extra set of threads on top of the other set - effectively ruining the show..
So I ended up taking the full depth of cut in one pass, and turning the lathe gentle by hand while doing it, still with the feed engaged. That worked OK.
But basically I knew that this lathe isn't top notch, but I never figured that it was this bad.
If you get a chance to get your hands on a lathe I can only suggest that you go for it.
Basic turning skills isn't hard to learn, and it is satisfying to be able to make a few metal object once in a while.
If you want to make a standard thread like UNC or something that you can get a tap and die for you can also do that on the lathe, just turn the object to the desired outer diameter and support the die on the tailstock.
I actually find that a metal lathe is a bit easier to use than a wood lathe. There are handles that will do an automatic fed lengthwise and crosswise.
Brgds
Jonas
Awesome, like Ralph, I too would like to be able to make small parts.
ReplyDeleteMy girl friend was a trained machinist and worked in a ship yard, before ending up driving a school bus. A lot less macho world if you asked her, there was not many women in the trade back then...
Maybe I should buy her a metal lathe :-)
Bob, with Rudy on my lap.
Hi Bob.
DeleteThat is definitely not a very usual trade to be a female machinist and working in a shipyard. Very impressive in fact.
I definitely think that you should buy her a small metal lathe if you could find one. not too small though. It needs all the correct functions and some of the very small lathes can't do thread cutting.
The most prohibitive thing in starting metal turning is that the initial investment of a lathe is kind of expensive. But like woodworking, it is a fascinating world with plenty of different challenges to keep you on your toes.
I have always admired model engines, they need to be mad with the utmost precision to be able to work, and there is just something attractive about a small steam engine with all the little details gleaming.
Give Rudy a scratch behind the ears from me.
Brgds
Jonas
Jonas,
ReplyDeleteAs often your post brought smiles. I grew up above and even worked in my Dad's machine shop for several years before college. I learned to work the lathes from some crusty old guys that loved to give the boss's son a hard time.
ken
Hi Ken
DeleteSomehow I can imagine that being the boss's son might not resulted in the easiest treatment :-)
I think it is about time I tried to teach Gustav how to use the lathe. He is really skilled with his hands, so a bit of instruction and he should be able to do some simple turning.
Brgds
Jonas