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

[SouthernChap]

No, you got $500 of scrap that you will put $1k into........

Way to be constructive and welcoming to a beginner machinist and a new member.

If you can't offer the OP constructive help, but can only **** on their cornflakes then I'd say you shouldn't haved posted anything.

If you believe for some reason that the lathe is beyond salvation then take a more humble tone and explain specifically why with this model, any effort/money would be wasted.

The world of machining for a beginner is intimidating enough, without people being harsh and this forum is meant to be different from the other places where the post you made would be par for the course.

 

[GrifterGuru]

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.

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.

 

[WobblyHand]

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?

 

[GrifterGuru]

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?

Yes, 7x lathes have earnt the criticism they face and for good reasons, though many of those reasons can be overcome with time, patience, work and, occasionally, a little money.

Yes, 7x gears are mod1 (closer to 0.98) and all have a boss to give a uniform gear thickness across the change-gear train.

For a 7x, all gears apart from the reverse tumbler gears are keyed. They have to be keyed since they drive the leadscrew and need to do so without slipping.

As for the Real-Bull 7x, I would imagine they are the same as all other 7x with all gears, other than reverse idler gears, being keyed.

Here is a list of the "usual" gears in an Imperial or Metric change-gear set, with a list of the "optional" gears.

 

[WobblyHand]

Lastly, what are the key way dimensions? Then I can design the gears. FreeCAD has a gear design workbench, it is pretty easy to knock out a basic design.

 

[GrifterGuru]

Lastly, what are the key way dimensions? Then I can design the gears. FreeCAD has a gear design workbench, it is pretty easy to knock out a basic design.

Gear keyways depend on the manufacturer. Even though they should all be the same, they are not. They do vary.

I have had to open gear keyways on gears before now, so I can only suggest that the OP @6Sally5 measure the width of the key and the depth of the keyway of the gears..

 

[markba633csi]

Good idea to check this type of machine early and thoroughly to catch any problems. Even so, we have had reports of motors and
electronic speed controls malfunctioning in a short period of time, poor machining on surfaces and bores and broken castings, so even tho it may not be total scrap they often come close. Certainly more problems than a beginner should have to deal with. A beat-up Atlas would be a better choice because most all parts are available, the documentation can be depended on and the price is comparable to these new imports.
That's why I advise folks to avoid these. Precision Matthews, Grizzly, and Little Machine Shop are much preferred. I have heard MicroMark is ok.
Stay away from Vevor and Bolton

 

[GrifterGuru]

Good idea to check this type of machine early and thoroughly to catch any problems. Even so, we have had reports of motors and
electronic speed controls malfunctioning in a short period of time, poor machining on surfaces and bores and broken castings, so even tho it may not be total scrap they often come close. Certainly more problems than a beginner should have to deal with. A beat-up Atlas would be a better choice because most all parts are available, the documentation can be depended on and the price is comparable to these new imports.
That's why I advise folks to avoid these.

Sensible observations.

Thats said, most beginners/new to the hobby people do not have the knowledge required to properly or fully check-over a pre-owned machine and that is where a lot of them are tripped up by thinking "new machine, no wear or problems" and that is the "gotcha" of it all. Whilst it can be the case with expensive/better quality machines that there are zero or very minor problems such as minor adjustment to Gibs or gear meshing, that is not, as you say, always the case.

Every 7x, heck every machine no matter what it is, should be gone over when it is taken out of the crate, no matter who sold it or who the manufacturer is. There is always something that needs sorting out, adjusting or dealing with.

 

[WobblyHand]

If the OP can provide the key way info, I can add this to my 55 tooth gear model. Was pretty quick to model. Once I know the key way info I can add it to the model and send you the stl file. A key way is just a subtractive groove to the model.
But yes, do check out the rest of the lathe, to make sure it's worth putting time and effort into. FYI, all I need to do is put in a different number of teeth and the gear is automatically drawn. The hardest part was fusing the boss to the gear - I had forgotten how to do that, but it was easy to figure out.

 

[GrifterGuru]

@WobblyHand

Not sure if this will help, but here is some info from a SIEG SC3 40T "POM" (Polyoxymethylene) plastic gear:

Keyway: 3mm wide, 2mm deep with 1.2mm of boss outside of that.
Centre boss: 18mm diameter by 7.6mm thick.
Gear is 7.75mm at the teeth

Seems odd to me that the boss is 0.15 narrower, but that is how it measured out and I did remeasure several times to confirm it.