29K70/71 - Making my own parts

[Snakeoil]

As I mentioned in my first post about me new to me 29K70, the take-up lever adjuster was missing from the end of the piston. Plus, the piston turned out to be for a 29K71 machine. I suspect the change was an upgrade for the K71 as it provided a click adjustable range for the take-up lever where the K70 was a simple screw and lock nut. The actual Singer name for this assembly is Check Lever Thread Take-up Adjusting Screw with Indicator.

Nobody seemed to have those parts so with dismal weather outside, went down to the basement to make the parts from scratch.

I'm going to do my best to use the terms that Singer uses for these parts. Owning one of these machines is like learning a new language. There are photos below that use the same item numbers as the 29K71 Parts Diagram. The numbers are referenced in the write-up.

First order of business was determining the thread pitch for the female thread in the piston. Turns out it is a 5/16-28. No part of the Unified system so no taps in my machinist chest. Used a piece of 1/2" cold rolled steel to make the Indicator Body (14) and single pointed the thread on my lathe and using the piston as a thread gauge. Next was the Locknut for the Indicator Body (15).

Locknut was another single point thread operation. But at a minor thread diameter of 1/4" it required one tiny little threading tool. Ground one up and made the nut. Hex for the nut was cut on my little Altas horizontal mill.

The Adjusting Screw (11) was made from a 1/4"-28 bolt. I had to cut additional threads on the bolt shank. But being a UNF thread, this was a simple matter of running a die down the shank. With that done, turned the plunger portion of the Adjusting screw to 5/32", which is a size I arbitrarily chose. Left enough wall thickness for the 5/16"-28 Indicator Body thread and was beefy enough for the application, which is adjusting the position of the Take-up Lever. I think I am going to case-harden the end of the adjusting screw where it contacts the Check Lever.

Next was the Index Head (9) which was made from another piece of 1/2" cold rolled steel barstock. Knurled one end and then drilled and tapped 1/4"-28 to fit on the Adjusting Screw.

Last part was easy, the Lock Nut (8). Just took a standard 1/4"-28 nut and faced it down into a nice thin jam nut.

 

And before somebody pipes up and say that I left some parts out, I know. The tiny spring and plunger that provides a click stop type of adjustment for the Index Head has not been done yet. First order of business will be finding a tiny spring. I'm thinking an old spring from the flint in a cigarette lighter. The stop pin is also missing. I believe the stop pin allows only one revolution and butts up against the plunger in either direction. But my checking of the total travel of my Adjusting Screw relative to the amount of adjustment available for the Check Lever resulted in my set-up having 3 turns of range. So, I will probably not use the stop pin. I also have to cut the V-notches into the Index head for the plunger stop points and put indicator marks on the Index Head.

Here is the assembled Check Lever Thread Take-up Adjusting Screw with Indicator.

When this is done, next order of business will be restoring the stitch length to full spec. I suspect I'll be removing the head and either brazing or welding up the tab on the bell crank and then hand filing to spec of 5mm diameter.

I now understand why this was an upgrade to the later 29K machines. It gives the machine the ability to put a little more positive tug on the thread versus relying on just the spring pressure of the Check Lever Spring.

Regards,

Rob

Edited February 8, 2020 by Snakeoil

[mikesc]

Thank you for posting..
My kind of thread ( 'scuse the pun ) ..
:)

[Constabulary]

Excellent !!!

The "new type" regulators are hard to find so maybe you could make a few more.

Pretty sure sooner or later someone will need one of these. But not sure if it is worth your time.

[jimi]

Well done Rob, Parts look great. 

[Snakeoil]

Thanks for the kind words. The only way to make these parts economically would be on CNC equipment. I'd be more open to making one for someone in trade for similar services or parts. I make custom pieces for fellow shooters, mostly just because they are friends and have shared their experience with me to help me improve. I'm always surprised to have one of them hand me something for one of my rifles without me asking.

Jobs like this are my winter therapy. I'm not one to read the paper or sit on the couch and watch the boob tube. Blathering on forums like this (I really only participate in 3) is probably my only vice where I'm not really doing anything "productive". I always try to contribute, even if a newbie to the topic and this post was intended as a contribution, not self-indulgence, Facebook, lookit what I did, kinda thing. Although I have to admit, I'm normally proud of how things turn out so I guess there is a little "lookit what I did" mixed in there. I touch type (thank you high school typing) so I know I can get a bit wordy. But the goal is to be clear.

By the way, the damn hex I cut on the indicator body lock nut is not perfect. I tried to take too big a cut in the mill and the piece twisted in the collet. It cleaned up about 95%, but I still can see it and it bugs me. But the machine is not perfect so it kinda fits in.

Today, my search  begins for the tiny plunger spring I need. If I find one, I should be able to finish the assembly today.

Constabulary, can you confirm that the stop pin on the Index Heal only allows for one turn of the head? And do you happen to know the pitch of the adjusting screw thread. I'm not going to change it now, but am curious how close I got.

regards,

Rob

[mikesc]

Plunger spring..maybe in the heads ( behind the ball bearing ) of the "click on" square drive in busted ratchet wrench..? Singer appear to have made up many of their threads and pitches as they went along..even on the same machine.
There was someone posted here once ( he did not hang around ) that he had a full set of taps and dies for all Singers..even the old ones..But he never demonstrated that it was so, despite much interest from members..A set of those would be more valuable/ useful to some of us than unobtanium.

Don't apologise..great thread.. :) very interesting..

Constabulary, or Jimi, or shoepatcher may well know the pitch ..

Edited February 8, 2020 by mikesc

[Snakeoil]

Well knock me down and call me Nancy. I went down to my Dental Cabinet (not mine. Given to me by a friend from his days in dental school) where I keep lots of tiny parts, screws, etc., and found not one, but TWO tiny springs. No idea where they came from or  how long I've had them. Both were nearly the same OD. Short one (which I used) was 0.082" and long one was 0.084".

Drilled the Indicator Body with a #45 drill (0.089") and machined a plunger to 0.087". Rounded the end and polished. Then case hardened the end and repolished once hard. I still need to harden the Index Head. Although I doubt I'll ever move it enough to cause any measurable wear.

I don't have any tiny number stamp so I cannot mark the Index Head. I refuse to do it with a vibro-engraver. Maybe I'll just put hash marks on it. Afterall, if I cannot count up to 8, I probably should not be running machinery.

Here are some pics.

[dikman]

Like mike, I too enjoy reading posts like this. I'm impressed, that's some nice delicate machining, particularly cutting the threads!

[mikesc]

I don't have any tiny number stamp so I cannot mark the Index Head. I refuse to do it with a vibro-engraver.

Laser ?
500 dpi is average for the cheap to mid range ones..that can etch metal..the cheap ones ( diode , not CO2 * ) can do metal ( Alu..and sometimes some Steels ) if you paint the area that you want to etch first.

Dental cabinets, lathes..precision cutting tools, cnc gear ..you looking to adopt anyone :)..or visitors who'll cut the lawn , take out the trash, do dishes ..in exchange for use of your atelier ... :)

*the 2 in CO2 should be "subscript"..but I'm not logged in ( when I do login the "push" on site crashes my customised FF ) ..and I can't remember if J has the boards set up to allow the more "esoteric" stuff in HTML..Best not to anyway..restrict what can be posted is the best security.

Edited February 8, 2020 by mikesc

[Snakeoil]

Buying a laser engraver never crossed my mind. I took a look and they are not terribly expensive. I've considered making sights for vintage single shots and the limiting factor was the ability to engrave the windage and elevation markings. Might have to think about this a bit. Thanks for the poke.