29k15 shuttle gear remanufacturing

[jimi]

Agree, that looks great that jacket, and with a speedy stitcher!!! Well done!

16 hours ago, 29k15engine said:

any help would be appreciated, especially if you speak spanish as i do not.

well i would normally help you in this case my friend but i have had a rifirrafi with this guy from Sitomaco and FINALLY after a year of phone calls and emails (most of which he did not answer) he refunded the parts i sent back to him. Some parts fitted and others did not? so you might have better luck.  

[29k15engine]

Thanks jimi,

I used google translate, then took a chance and ordered the parts. Hopefully these parts are what i need. I think the k1 machines used the same follower gears as the k15 just in a configuaration of 3 gears not 2 and a short rack, time will tell.

Im quite interested in making gears for these, i really need a hobby lathe or mill, or make a small dedicated machine to cut these. The more i learn about gear cutting and " hobbing" the more doable it looks.

The rack would also need to be made which could if i was to make it have a length adjustment built in to fine tune shuttle timing.

 

[jimi]

21 hours ago, 29k15engine said:

the 4th picture shows what my gears look like.

Mmm... the 4th picture is of the 29ks that had the detachable gearbox?? If you have a K15 you will have 3 pinions??

[29k15engine]

Sorry jimi mine is like the one on this thread above. This one

 

 

[DonInReno]

For a number of years I've been surprised that someone in a home shop hasn't started producing replacement gears - my guess is the labor costs are just too much to have a reasonably priced part, not to mention there is more to getting a worn out machine to work than just changing gears.

There are a number of good introduction videos for cutting gears and racks.   However, as Mr. Pete says in one of his videos, all it takes to machine a $10 replacement gear is a $5000 milling machine, $2000 in tooling and an entire weekend of messing around with setup.

Gears can be made in many different configurations and sizes - as with Singer's tendency to build machines with oddball screw sizes, my guess is their gear patterns are slightly off from any standard size.   It can be confusing at first sorting out all the information, but just keep in mind metric gears use a different system of measurement and cutter geometry, so ignore that and just look to old school American standard gear information.  All Machinist Handbooks have sections on cutting and measuring gears that would be helpful for anyone serious about getting set up to make gears.  Still, a machinist could come close to oddball gears with readily available tooling and fudging the dimensions for a one-off set of gears if the machine was in front of him.   That's the most expensive route.

Fully machined gear racks and rough length pinion material is readily available.  Using these a machinist would not have to cut the actual gears, but would still have to machine the dimensions to retrofit them to the machine - not a trivial task.

I know of at least one person who has replaced the entire lower arm with one machined from from a solid bar of steel along with new gears and rack as described above.   This was definitely more a matter of bragging rights and the enjoyment of machining, rather than something for profit since the time involved must have been significant.

The high strength epoxies are often used to attach wear strips to worn out parts in industry as an alternative to more invasive repairs.   As CowboyBob mentioned, brass strips are often used on a worn rack to reduce clearance between gears.   Likewise, it wouldn't be impossible to epoxy a partial cylindrical metal band to reduce clearance in the hook area, but the time involved would be prohibitive and the wear is not in an even circle so it would have to be machined round for the shim to have any chance of working correctly.

Having said all that, I'm humbled by clock makers that would simply cut, file and fit all the gears by hand - the skill set and time requirements are quite impressive.

My prediction is that the proliferation of higher and higher precision CNC machines for the home shop will produce a regular Ebay or Etsy supply of gears for these old machines in the near future.

[29k15engine]

Just done a render of the rack on a 29k15 which would be a soldered on item that would replace the end of a worn out rack.

This is acurately measured and constructed therefore I need to make one to see if it works, I have a friend with a 3d printer who can also make one out of steel at work from a 3d file.

 

 

Edited June 28, 2021 by 29k15engine

[29k15engine]

the cog as well, though this may need work. you get the idea though.

 

 

[jimi]

Looking good! 

I would think welding a new on on could be tricky?? the newer types have a eccentric screw to adjust them, just a idea... if it could be fixed with a screw after cutting off the old worn one then drilled and pinned after adjusted?? 

Edited June 28, 2021 by jimi

[29k15engine]

Thanks jimi, I put soldering/welded as I found this intriguing parts listing.

 

[29k15engine]