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

WobblyHand said:
If you tell us the bore of the gear, it's thickness, and it's module, it's possible to design a gear to print. Can you measure the diameter of one of your gears and tell us how many teeth it has? From that, we can determine the module. tip diameter = module * ( 2 + number of teeth)

For instance, your 60 tooth gear. module = tip diameter/( 2 + 60 ).
Click to expand...
Thank you sir!

The bore of the 60-tooth gear is 0.467 inches.
Thickness is 0.275 but has a .793 inch o.d. boss on one side that is .038 thick…bringing the overall thickness at the boss of .312.
Diameter is 2.432 inches
 

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VicHobbyGuy said:
Does it look like this?
View attachment 501091

http://www.yishoumachinery.com/en/pd.jsp?recommendFromPid=0&id=19&fromMid=311

That's a pretty standard 7x14 mini lathe made by RealBull.
I had one much like it, and after some 'tune-ups' it worked fine.
Plastic change gears work fine on those lathes, and can be made easily on a 3D printer. The files are online; gears are very easy to make suing CAD like OnShape (there's a plug-in), if that interests you.
Check the bore on the change gears - it may be different than the bore on the change gears for the more common Sieg 7x lathes sold by Grizzly, Harbor Freight, LittleMachineshop (LMS) etc. You can get Sieg gears from LMS, and 'everywhere' online.
Change gear calculator is at the LMS website, BUT to use the calculator you need to know whether your lathe has a metric (1.5mm) or 16TPI Imperial leadscrew.
https://littlemachineshop.com/reference/change_gears.php
My Vevor had a metric leadscrew. Since your lathe chart is calling for the 40/55 gear combo to get to 20 TPI, it has a metric leadscrew. It probably doesn't have a threading dial?

LMS also has operating manuals.

If you aren't allergic to Facebook, there are a couple of good 7x lathe groups there. More knowledgeable (about Chinese 7x lathes) crowd over there, too. :)
Click to expand...
Yessir…that’s it. I have taken this thing apart, cleaned, lubricated, squared and reassembled. It works pretty good so far. It does have a threading dial. I am a long time woodworker and metal stuff is brand new, but like Quinn from Goldihacks says, “For all you woodworkers discovering machining, there’s a whole new world below a 16th of an inch.” Boy…that’s an understatement!
 
6Sally5 said:
Thank you sir!

The bore of the 60-tooth gear is 0.467 inches.
Thickness is 0.275 but has a .793 inch o.d. boss on one side that is .038 thick…bringing the overall thickness at the boss of .312.
Diameter is 2.432 inches
Click to expand...
I'll calculate it out tomorrow, but that's helpful. Generally, these lathes are all metric.
 
WobblyHand said:
If you tell us the bore of the gear, it's thickness, and it's module, it's possible to design a gear to print. Can you measure the diameter of one of your gears and tell us how many teeth it has? From that, we can determine the module. tip diameter = module * ( 2 + number of teeth)

For instance, your 60 tooth gear. module = tip diameter/( 2 + 60 ).
Click to expand...
I think all the 7x lathe change gears are module 1 metric.
 
6Sally5 said:
The bore of the 60-tooth gear is 0.467 inches.
Thickness is 0.275 but has a .793 inch o.d. boss on one side that is .038 thick…bringing the overall thickness at the boss of .312.
Diameter is 2.432 inches
Click to expand...
Especially with a 7x lathe, it's much easier to work in metric.
You'll probably need at least some metric drills, and preferably reamers to get the gear bores to match the shafts they should slide on to. On my lathe, the plastic gears seemed to have been put on with a hammer. :)
 
7x lathe change gears can be a devil to fit. I ended up running a reamer through all of the change gears, both the metal set for the lathe I am rebuilding as well as the plastic ones on the SC3. Made a world of difference and no more tapping to get them on or off.

Some gears have to be purchased separately to gain a full combination imperial and metric set.

Watch the key slots in the change gears too, they can either be too shallow, too narrow or a combination of both. I went with a four-square needle file to debur and open out the key-slots to ensure a good sliding fit.

Make sure you have plenty of lubrication on the twin-gear idler bush that carries the 80/20 gears. The one on my SC3 siezed to the shaft despite being lubricated because it was slightly undersized. I made a new one and ensured it had proper clearance, though I did rob the one from the lathe I am rebuilding to finish what I was doing at the time, then put it back once the replacement was fitted.

When changing the change-gears use a slip of 80gsm printer paper or a post-it note between them to set the mesh.

Another tip, always have at least one plastic gear in the chain. Better to strip the teeth of a plastic gear than to cause greater damage elsewhere. I left the idler gears on the reverse lever as the weak-point so those are the ABS/Plastic gears. Easier to replace and cheaper.

Most 7x lathes are supplied with metric lead screw, cross-slide and compound screws and rests. You can convert them to imperial if you wish to spend money on imperial lead screw, coss-slide screw and compound rest block, feed screw as well as replacement cross slide & compound slide dials. Metric dials have 40 divisions, Imperial dials have 50 divisions.

Imperial leadscrew is 16tpi, cross slide and compound slide screws are 3/8" 20tpi. Left handed for cross slide, right handed for compound rest and feed screw.

LittleMachineShop.com sell the parts to convert to imperial.
 
GrifterGuru said:
LittleMachineShop.com sell the parts to convert to imperial.
Click to expand...
Do they sell parts for Realbull lathes now? I thought they only sold Sieg-compatible parts. The leadscrews are different - at least they were comparing my Sieg Microlux and RealBull Vevor.
 
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