Gear help needed

Suzuki4evr

Suzuki4evr

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Hi guys.

I don't know where I went wrong,but I need some help. I made a set of change gears for my big lathe and I actually posted another thread about this,but I wanted to post a new thread for all to see who maybe able to see where I went wrong. Please bear with me if this is a bit long.

It is four gears and here is the configuration.
20201208_105706.jpg
Now three gears worked out as planned, but the 57 tooth gear blank finnished with 60 teeth. NOW HOW THE HECK DID THAT HAPPEN. When I put all four gears next to each other, they still mesh but somehow the "57" teeth,that is now 60 teeth,just will not fit when on the machine.
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It looks like somehow the OD of the 57 tooth gear is to big,but I can't see where I went wrong. So I will give the information I think you need to HELP me see if I made a calculation mistake.

Here is the info for the gear Module=2.
N=57
With this you are supposed to be able to get the OD for the blank and from there all the other information needed to make the gear.....right? And that gave me 118mm. Could the centre distance between the gear and Idler gear influence the OD of both gears? And with the given chart I have wich came with my Vertex dividing head I must use a 33 hole plate and move every 22 holes to make a 57 tooth gear,but what I found very interesting looking for my mistake today is this.
Screenshot_2020-12-08-22-24-48-1.png
What I found interesting is that to make these three divisions, for all three you need to move 22 holes on a 33 hole plate and 60 is one of them. Is that coincidence or what?
PLEASE HELP ME!!!!!!!

If any other information is needed, please let me know and I will post it tomorrow, because I don't have it with me right now.

Thanks in advance.
Michael.
 

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What happened, is that 57 is a prime number, and cannot be divided without a universal dividing head with change gears, on your chart, the change gears are noted beneath the other info for 57 divisions. I am assuming that your dividing head is not equipped to do this, but if it is, you need to use the indicated change gears, 48, 24, and 40 teeth. Other than that, nice looking job! On most lathes, the "banjo" that holds and positions the gears is capable of adjustment for proper mesh.
 
If you were able to make a 57 hole plate, I think you could accomplish it that way without having a universal head, I do know that the numbers of holes is limited by the relatively small diameter of B&S type plates, 39 being the highest number in the set, and the holes are pretty closely spaced at that. On the gear that you made, since it is a small diameter for 60 teeth, the teeth would have a smaller chordal thickness that one cut with the proper number of teeth.
 
I forgot to mention earlier that this method that uses the change gears is known as differential indexing, the process gears the work spindle of the dividing head to rotate the index disc either in one direction or the other while the index crank is rotated.
 
I would think the OD was a tad big...ran it on this calculator....indeed 118mm is correct. Above my pay scale!gear.jpg
 
benmychree said:
What happened, is that 57 is a prime number, and cannot be divided without a universal dividing head with change gears, on your chart, the change gears are noted beneath the other info for 57 divisions. I am assuming that your dividing head is not equipped to do this, but if it is, you need to use the indicated change gears, 48, 24, and 40 teeth. Other than that, nice looking job! On most lathes, the "banjo" that holds and positions the gears is capable of adjustment for proper mesh.
Click to expand...
I do have a universal dividing head also,must just check if I havea all the gears,because I picked it up at the scrap yard. The banjo part on wich these gears are sitting has a fixed distance between them but can be set for the up gear clearance.
 
benmychree said:
If you were able to make a 57 hole plate, I think you could accomplish it that way without having a universal head, I do know that the numbers of holes is limited by the relatively small diameter of B&S type plates, 39 being the highest number in the set, and the holes are pretty closely spaced at that. On the gear that you made, since it is a small diameter for 60 teeth, the teeth would have a smaller chordal thickness that one cut with the proper number of teeth.
Click to expand...
I guess I coul make one using the DRO on my mill right?
 
Just got in the shop and checked if I have change gears for the universal DH. I do have the 40 & 48 but not the 24. But I have another problem. Seeing that I got the DH at the scrapyard,there is some gears and parts to fit the gears on,missing. It will take time to make all these components, so I think for this project I must make a 57 hole plate using my DRO. What do you guys think?
 
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