Need change gear help with a Vevor model YS-1835-A mini lathe!

[6Sally5]

In many ways these lathes have earned criticism. But sometimes they can be fixed up to do credible work. Let's hope yours is in the group that only needs a little bit of effort to be useful.

As for the gears, the measurements validate a module 1 gear family. The OD appears to be 62mm from the picture. The bore is close to 12mm. The gear is 7mm thick and has a 1mm high boss that is 20mm in diameter. (About 1/3 the OD). Do the gears have key ways in them?

What sizes are missing for you again? Do all the gears have the boss? Meaning are they all 8mm thick?

Thanks very much, sir. When I told my SIL about my gear issues, he said he could 3D print them easily. I need the 55 and 65-tooth ones for now. It turned out that he spends quite a bit of money at Little Machine Shop and knew from their site the necessary program for his printer. He knocked them both out in a couple of hours. The bore is smaller but I can fix that on the lathe.

 

[WobblyHand]

Great tips and info! Do you recall what size reamer you used? My SIL was able to make the 55 and 65 tooth gears using his 3D printer and the data from LMS. The bores though are .009” smaller than the factory gears.

You can either press them on, or use a reamer of the right size, which is 12mm, not 1/2". Lacking a reamer, you could use a 12mm drill bit by hand. Or perhaps you can adjust the print settings in the slicer to slightly open up the bore. The ID of holes when printed often are slightly narrowed compared to spec. Sometimes this is due to slight filament ooze, or simply a slight elephant foot at the first layer. Perhaps only a slight chamfering with a round file on the first layer would help.

If all else fails, you have a lathe and you could bore it out.

 

[6Sally5]

I do have a mini-lathe. But I am NOT assuming that what I have (Sieg based) is what the original poster has. Which is why I asked the questions. More than happy to make a couple of designs, to help out, for a few missing gears. Not so keen to do a full set, well because that starts to look like work.. As noted above there's loads of change gears online, but it's not always obvious what their dimensions are, because stl's are tough to dimension from.

I figured the key way might be 3mm, but wasn't sure about the height of the key way. If I recall correctly, the needed gears were 55 & 65? Anyways, here's the stls for 55 and 65, with my best guess at dimensions. 3mm key width, 2.5mm long from radius to end of key. And the FreeCAD file if anyone wants to play with it. Just select the grey gear on the side and you can change how many teeth there are. Once you do, the gear is redrawn. Then export the Body to stl, or step. Easy peasy. Happy printing.

Thank you sir! This was a lot of work for you, I’m sure and I very much appreciate it!

 

[6Sally5]

You can either press them on, or use a reamer of the right size, which is 12mm, not 1/2". Lacking a reamer, you could use a 12mm drill bit by hand. Or perhaps you can adjust the print settings in the slicer to slightly open up the bore. The ID of holes when printed often are slightly narrowed compared to spec. Sometimes this is due to slight filament ooze, or simply a slight elephant foot at the first layer. Perhaps only a slight chamfering with a round file on the first layer would help.

If all else fails, you have a lathe and you could bore it out.

Thanks. Your last comment is funny because when I suggested to my SIL that I could run a drill through the bore, he said, “Alan….you have a lathe now!”

 

[6Sally5]

To all responders, thank you very much for your help and work providing the stl files (whatever those are…I’m not a machinist yet ). Thankfully I have a very talented SIL that knows what to do with them!

 

[6Sally5]

TBF, I have purchased parts that fitted without issue to a non-Sieg (Crenex as it was before the rebuild). Leadscrews, cross slide screw+nut, half nuts, compound rest, compound feed screw, dials for compound slide and cross slide. All fitted without issue.

The only thing to watch is whether the leadscrew is for a 14" or 16" bedway and whether you need change the right hand leadscrew pillow-block to suit the new leadscrew.

Question…what is a pillow block?

 

[GrifterGuru]

Question…what is a pillow block?

The Pillow block is the bracket that holds the end of the leadscrew and supports it. There is one at each end of the leadscrew.

 

[GrifterGuru]

Great tips and info! Do you recall what size reamer you used? My SIL was able to make the 55 and 65 tooth gears using his 3D printer and the data from LMS. The bores though are .009” smaller than the factory gears.

12mm Reamer.

I followed that up with a chamfer around the ouside of the bore.

 

[VicHobbyGuy]

Do you recall what size reamer you used?

I bought a bunch of reamers after I got my 7x lathe and 'went metric'.
https://www.aliexpress.com/item/32901164101.html
You can get the same thing, more quickly, from Amazon. Double/triple the price, but sometimes I don't want to wait a couple of weeks for a tool.

 

[homebrewed]

A 12mm drill would be cheaper than a reamer. But you still could be looking at ordering it, metric drills aren't quite so readily available here in SAE land.

The problem with using a lathe to bore it out is that the hole is on the small side. The boring bits commonly sold for this kind of machine aren't going to work very well, if it all. They will rub on their heel, not cut at the tip. I've used small end mills for this kind of thing but that's only helpful if you have one on hand.

Long ago I bought a set of brazed-carbide boring tools for my lathe. Only one or two of them are usable right out of the box. The rest are just an exercise in frustration. They need to be ground to achieve the right cutting profiles due to the abysmal manufacturing process they went through. On the other hand, my CCMT-insert boring bar cuts like a dream. Something to consider if you decide to bore out those gears of yours.