29k15 shuttle gear remanufacturing

[DonInReno]

On 6/28/2021 at 2:15 AM, 29k15engine said:

 

 

 

 

Good job on your progress!    Your measurements show a pressure angle of 9.2 degrees, while many/most older gears were 14.5 degree and most gears used today are 20 degree.      Obviously non of the readily available involute-profile gear cutter tooling would be of any use - probably why it’s rare to find anyone who has done this.

 I find the tooth profile on the rack interesting - involute-profile racks have straight sides where the pinion actually makes contact, where the slight curve on the upper portion of the tooth shows these are pretty unique compared to most older gears profiles.

I’m wondering out loud if this is a cycloidal-profile style of gear such as was used in clockmaking.   On the following page it mentions that on pinions with few teeth the involute-profile becomes difficult to manufacture, and cycloidal makes more sense.     https://www.csparks.com/watchmaking/CycloidalGears/index.jxl

Looking forward to seeing progress!
 

 

[29k15engine]

Hi Don, feel free to think out loud, having modelled the gear as well I have tweaked both to do the 3d print, here are the latest drawings. I got the gear and rack to mesh with 0.001mm and no interference on full rotation with all 3 gears in correct position, so we will see when my friend pops round with the prints.

In my book it talks about lantern gears which were very round. My final drawings are not as round so we will see how they actaully mesh.

 

Edited June 29, 2021 by 29k15engine

[29k15engine]

Just found from a supplier I can get parts

8608 Following Pinion for both 29k1 but also following pinions for 29k15 and the like.

8599 Small rack

plus

8600 long rack!! which I may be able to be modified to fit a 29k15 with an adjustable rack rod.

These are all new parts.

Will keep you informed on these as it is another direction to get these parts working the older machines.

Here is a picture from the supplier of part 8600 in stock.

 

[Wizcrafts]

Awesome find!

[29k15engine]

Ok so my pal dropped of an evelioe with the parts he made on his new 3d printer.

I was hoping for the best but like all things engineering prepared for the worst... however they fit!! Like a glove

I need to tweak the end of the gear tooths a little but first fit is good. As the tooth end is a little too accurate they need a micron or 2 more clearance.

Have a look, comments and critique welcome.

Edited June 29, 2021 by 29k15engine

[chrisash]

Are you looking for the end product in steel or Nylon' for the gears, I doubt the bar would stand up long term in |nylon but the gears should

[29k15engine]

Steel these are just for prototyping

[29k15engine]

Ok just done some measuring compared to my good gears, the differences are 0.1mm on cog tooth thickness ie prototype is thicker and diameter of cog overall needs to be .2mm less apart from that not alot needs to change.

Have a comment if you can critique more the merrier.

 

Her are the parts fitted to the base plate, little tight but these changes may be all that is needed.

 

 

[29k15engine]

Video of parts moving also shows where they need a shade more room to move

 

29k15 shuttle prototype video

Edited June 29, 2021 by 29k15engine

[29k15engine]

Ok I have revised the drawings over the past few days, is is the most accurate. I used a microscope to image both the cogs and rack.

 

Nearly there now.

 

 

[chrisash]

Don't forget the tolerance's in 100 years ago were far larger than todays , also PLA has quite large growth when printed on some objects, I did try making some Nylon printed gears and that had far more stable size.

I would suggest using Fusion 360 for the design and you can test the fit using the program before you print

Edited July 1, 2021 by chrisash

[29k15engine]

Excellent thanks Chris,

My friends 3d printer is a ELEGOO Mars Pro MSLA 3D Printer so prints with more accuracy.

We are having a go with a Wire EDM machine to try it in steel to make 1 prototype , we will see.

It good work to see how accurate these processes really are.

Im also looking at having them laser cut but am unsure on the accuracy needed if I went this way.

Edited July 1, 2021 by 29k15engine

[chrisash]

You need to accurately measure your finished items and then make a percentage adjustment to your slicer to get the best results, all 3D filament's react slightly different on different printers

[LindanHotAir]

17 hours ago, 29k15engine said:

Excellent thanks Chris,

My friends 3d printer is a ELEGOO Mars Pro MSLA 3D Printer so prints with more accuracy.

We are having a go with a Wire EDM machine to try it in steel to make 1 prototype , we will see.

It good work to see how accurate these processes really are.

Im also looking at having them laser cut but am unsure on the accuracy needed if I went this way.

You could also check out using a water jet cutter. It wouldn’t have the same thermal effects as a laser.

[DonInReno]

Wow - a wire EDM should make short work of it!   Great work!  Your project has me reconsidering a worn out patcher - in the past I’ve steered clear of them because of gear issues.

[29k15engine]

Thanks people, after reading the specs of EDM i've been tweaking the gears and measuring my good gear over and over to make sure I give it my best shot.

I am also getting them to cut the bottom plate so I can put all the parts together.

Here is what is going to the EDM, on paper no interference issues.....we will see.

If and when I get this "right" I can then provide STL and DXF so people can get these parts made locally, though the tollerances are so tight I am also looking to make these myself to keep the quality and fit right, time will tell on this. I would love to do this the old fashioned way with dividing head and hobber but I don't have a lathe or enough knowledge of hobber design to get it right,,,yet!

 

https://1drv.ms/v/s!Arc9igKuarE5gSUtRwX55Ou3oxz-

 

The other research on parts still available is hopefully going to bear fruit. I have the following parts ordered from Ital and Spain.

8608 New pinion gear, I don't yet know if these are in short supply and therefore NOS "new old stock"

8600 New Rack for 29k1 but same rack profile as 29k15 range so can be cut and extended for use on 29k15 or as it on K1

8599 New Small rack used on K1 but could be a donor to be grafted to long rod for k15

So judging what these parts are like quality etc it will offer two routes to getting gears for these values and treasured machines where initially there was none.

I would also like to make an adjustable rack rod so fine tuning of shuttle movement can be achieved like the later machines.

One of the main drivers for me to do this is when I contacted the singer archives I was informed that most if not all of the singer designs and drawings were destroyed in the 80s when the factory was demolished, thats 150 years worth of engineering expertise translated to complex designs and drawings, to reverse engineer like I am doing you really appreciate what they achieved 100 years ago.

If these parts are preserved in computer formats that people can use to replace these parts then these machines could go on for another 100 years.

 

 

 

 

Edited July 3, 2021 by 29k15engine

[29k15engine]

Ok bit of an update, still waiting for my friend to cut the gears out of metal.

 

Meanwhile I have just recieved new follower pinion gears from spain, part no 8608 and found they are so close to what they should be but do not fit.

I will post an image of the gears, it seems that the teeth are too thick by around 0.38mm plus the root of the gear is not deep enough by 0.38mm

 

[29k15engine]

Ok so I got my new part 8606 following pinion which is used on the 29K1 machines in a 2 cog configuration with a long and a small rack as shown below and also on the 29k15 machines as a 3 cog one long rack configuration show below.

 

So as you know I have been modelling the cogs and rack for the 29K15. I have found a supplier of the cog which I have recieved today.

Unfortunately the cogs do not mesh with the 29k15 3 gear setup, this is due to a couple of dimensions being different, I am wondering if on the 2 cog design the tollerances of the pinion did not need to be as accurate as it is just picking up on 2 racks and not 3 cogs and rack.

Below is an image of the 8606 cogs recieved. One looks slightly different on the tooth from the other.

When measured against my good original gears that fit like a glove I find the dimensions below different.

The tooth is thicker 2.51mm not 2.16mm each tooth is 0.25mm thicker

and the root of the gear is not as deep 9.10mm not 8.48mm difference of 0.31mm shallower root to the gear

If I place the two new gears onto the lower plate of the gearbox the gears do not allow the gears to turn as there is no room for them to move.

So I am hopefull that the cogs being made by my friend on an EDM  machine will be better fitting than these.

 

 

 

 

 

Edited July 8, 2021 by 29k15engine

[29k15engine]

I am now working with the theory that the 29k1 machines did use follower gear 8608

then when the 29k12 came along they used 8608 but with tighter dimensions, looking at lots of gears now

even unused ones the K1 gears look thicker in the teeth, I do not put this down to wear as my gears are very very good but there is no way a fatter toothed gear would fit when meshed with the adjoining fatter gear.

Therefore Im going to press on with my 29k15 (im encompassing all the revisions from k12 to k15 and k20) gear modelling and cutting research.

[chrisash]

I dont know if this YT video would assist you  

 

[shoepatcher]

great Job 29K15engine!   I have been playing with these gears and rack over the last couple of years.  SItamaco in Spain has the 29K1parts made in China I believe.  They are new.  The drive gears, short rack, following gears, shuttle carrier and set screws are all needed today for 29-4, 29K1-33, 29K51-56machines.  Other than Sitomaco, no one is making them.  thee is a big need for these parts.  Singer made over 250,000 29-4 machines!   

Gear #8608 was used in 29K1-4,10-18,21-23, 32, 33. right of of original singer parts book.  I know no one is making gears for the 51-56.

glenn

[29k15engine]

Ok some progress

Hi jimi,

 

Bit of an update.

My new rack, parts number 8600 arrived today from italy, good news it is exactly the same as the 81899 rack used on the 29k12 29k15 etc , the only operating difference is it has one more tooth than the 81899. I cut this off and shaped the end, i also filed very slightly the back of the rack not very much at all, the hole needed 5mins of emery paper but after that the fit and quality is excellent.

One of the things i wanted to do was get the shuttle timing perfect, i wanted to add an adjuster but as i bought 2 i cut one in half and added 1.6mm to the length, this meant that the shuttle pickup is exectle where it should be, it now stitched reliable and very very .

 

 

[29k15engine]

Here is my shuttle positioning with the new rack adjusted by 1.6mm "lengthened" https://1drv.ms/v/s!AoQ4CZYzE-ZEjiZdA7ILSnPrUpr-

 

 

 

[jimi]

Hey Mat, you can make some leather jackets again now! 

[29k15engine]

Yes jimi as soon as I can find some leather that is not too thick but also not too thin! Seems to be harder than finding these singer parts lol