Spur Gears in odd bore sizes

[Zouave]

So, I ended up going with Motionking's motors, and just realized that the shafts are 14mm. So, knowing that now, I am faced with a bit of a dilemma. Namely, what do I do for the spur gears. I am seriously considering ordering the spur gear rod from McMaster, and cutting my own gears out. Am I crazy to even think about this? Or should I buy the 1/2" bore gears and drill it out to 14mm, or custom order it somewhere? I plan on doing a belt reduction drive, so I want whatever I get to be compatible, in the end, with that. Which means I am probably SOL. :-D Does the one thing I overlooked (14mm shaft) pretty much mean everything I'm doing is going to have to be 14mm now? (Bearings, pulleys, spur gears, etc)

Should I go ahead and build the reduction drive now, so that I don't have to bore out the spur gears to 14mm, and only have to bore out the timing pulley that goes on the shaft of the motor, and leave the rest at 1/2"?

Advice, suggestions, alternatives, magic? Anyone?

[bradm]

Hmm. Do you have access to a lathe?

I think I'd drill things out as necessary for the 14mm - first the spur gears, and then later the motor pulleys. Neither of those will take a lathe, but if you want to save the cost of another set of spur gears for your belt reductions, you could make shafting for the belt reduction that is 14mm at the spur gear, but 1/2" at the bearings and pulleys.

Drilling out the gears and pulleys is an easy operation, as is turning down the shaft.

[Zouave]

I guess I was mostly worried about drilling the hole on center. Should I get a 14mm reamer to have a more precise hole, or should I be okay with a 14mm drill bit and a grub screw?

I do have a lathe, just not sure how accurate it is yet.

[Gerald D]

If you have a lathe, start with a pre-drilled pinion . . . . . that is your best chance of getting the enlarged hole on center. You could get away with a new 14mm drill (maybe slightly oversize finish).

A reamer is rather expensive and doesn't help to center an off-center pilot hole.

[MetalHead]

I would do the belt drive setup and just buy a 14mm pulley. Then I would switch the secondary larger pulley back over to 1/2. I can help you with the hardware. I also have axles and flanges bearing sets. Let me know

[Zouave]

I will be checking the accuracy of my lathe today. (Just bought a 12" Clausing with a bunch of extras). If it turns out that it is on center, is there a good reason not to buy a 12" length of gear rod for $40, and turn whatever size I need, versus buying 4 gears at $20 each? I used to be a fairly competent machinist, just haven't had a lathe for a number of years. The idea of having an extra 8" of gear rod left over is fairly attractive too. I do have boring bars, so I have options other than just drilling with a 14mm bit. Just maybe not quite as fast and easy.

[Zouave]

... and then I realize that the gear rod is only available up to 20 teeth for a 20 pitch gear. I was pretty set on a 30t gear. Dang. Guess that ends that discussion. At least as far as McMaster Carr goes. Maybe I can find it elsewhere.

[Gerald D]

Eric, if you told us earlier that you are an experienced machinist, we would have given different advice.

[Zouave]

Used to be. ;-)

I sure wish the US would get on board with the metric system. Seriously. Finding 14mm parts in anything is such a chore!

[LizardKing]

Originally Posted by Zouave

Used to be. ;-)

I sure wish the US would get on board with the metric system. Seriously. Finding 14mm parts in anything is such a chore!

Best if we just gave up on metric completely.....

[Zouave]

Because what percentage of the world uses English measureme
nts...? :-)

[LizardKing]

Originally Posted by Zouave

Because what percentage of the world uses English measurements...? :-)

The English part of the world, of course!
That would be the part that MADE modern civilization and where most
goods go to be sold.
As a matter of fact after the English part of the world decided it would
be a good idea to switch to metric is when the English part of the world declined........

[Zouave]

Wait, what? The US is the only industrialized nation that doesn't use metric. Even England is in the midst of transitioning. Our military even primarily uses metric.

But aside from my whining about the difficulty of using products that are not manufactured exclusively for American consumption, we are getting a little off-topic.

[LizardKing]

Originally Posted by Zouave

Wait, what? The US is the only industrialized nation that doesn't use metric. Even England is in the midst of transitioning. Our military even primarily uses metric.

England had officially changed over completely but these days are in the midst of changing back.
America has become DE-industrialized since the call for metrication.

But aside from my whining about the difficulty of using products that are not manufactured exclusively for American consumption, we are getting a little off-topic.

It was a long time ago but when America WAS industrialized we made the best stuff that was used and respected world wide.
Bore out the gears and use them if you need to.

[Jason Marsha]

Originally Posted by Zouave

I guess I was mostly worried about drilling the hole on center. Should I get a 14mm reamer to have a more precise hole, or should I be okay with a 14mm drill bit and a grub screw?

I do have a lathe, just not sure how accurate it is yet.

You may want to drill at around 13mm and use a boring bar to shave off the extra which will give you a very snug fit.
You will have to keep checking the hole size with inside/outside calipers.

Jason

[LizardKing]

Originally Posted by Jason Marsha

You may want to drill at around 13mm and use a boring bar to shave off the extra which will give you a very snug fit.
You will have to keep checking the hole size with inside/outside calipers.

Jason

That will work or even better bore it a few thousand under 14mm and use the reamer for final sizing.
Chuck in the lathe in the 4 jaw and use the bore to center it.

[MetalHead]

I second the undersize drill and the reamer.

[Zouave]

Why not use a self-centering 3 jaw chuck? Mostly just wondering why the specific call for a 4 jaw. As long as the 3 jaw is running true, won't that work just as well? Or am I missing something?

Suggestions on size for the grub screw?

[Richards]

When I had to enlarge the bores on 1/2" pulleys to fit some Oriental Motor Alpha motors that had a 14mm shaft, I did everything on my Habor Freight mini-lathe. I drilled the holes to 13mm and then used a boring tool to get a "perfect" fit on the 14mm shaft.

Because the pulleys had flanges, I cut pieces from copper tubing so that the teeth on chuck could hold the pulley properly.

It only took a few minutes per pulley to properly align things and a few more minutes to drill and bore the pulleys.

[Zouave]

Originally Posted by Richards

Because the pulleys had flanges, I cut pieces from copper tubing so that the teeth on chuck could hold the pulley properly.

Did you do that just so you wouldn't mar the flanges? My gears have a shoulder that I was planning on gripping with the 3 jaw chuck (or 4-jaw if my 3 jaw isn't running quite true) and going in from the 'back side' of the gears. I think when I do my belt drive, I am going to have to bore out one pulley to 14 mm (the one that goes onto the motor shaft), and leave the other one at 1/2", so I can use standard bearings for the shaft that connects that pulley and the spur gear that will interface with the rack. I'll have to turn a custom shaft with a 14mm step on the end, the rest of it at 1/2, for that. I'll put together a Solidworks drawing of it later for people to look at and see if I'm thinking about things right.

[LizardKing]

Chucking it in the 4 jaw and indicating it out to get more accuracy.
Could put it in the 3 jaw and see how closely centered it is.

[Richards]

The shoulders on my pulleys were not concentric to the bore, so using the shoulders would have caused the bore to be off-center.

The flanges were too malleable to withstand the pressures, they were also not concentric with the bore.

In order to bore a hole concentric to the teeth, I used the copper pieces. It took a little time, but when I was done, the bore was the correct size and it was concentric to the teeth.

[sierra347]

Eric

Did you end up machining your motor pulleys to 14mm? I also went with the motion king motors and have not been able to track down 14mm bore pulleys.

[Zouave]

I did. Where are you located?

[sierra347]

I'm in Illinois, did you use the method Mike used. Before reading this thread I tried a drill press but failed miserably.

[Zouave]

I chucked mine in a 4 jaw chuck and used a dial indicator too center out.

[JasonC]

Lathe it, 4 jaw, carbide boring bar, dial indicator, calipers...it would take maybe 15 minutes. Take the 3 jaw chuck and make a paper weight out of it.

Thats what I did.

Jason

[JasonC]

What is I.D. pulleys do you guys have? There are other ways to skin a cat, maybe I can help if you dont have a lathe. 14mm is about .5511 of a inch. A 9/16 or .56inch ream could get you there if you have a drill press and some sort of cramping setup but I would go with a closer tolerance. The ream is about 10$US at grizzly tools.

The best is a 14mm reamer that is a .5512 hole size ream.


Jason

[sierra347]

The ones I have are 0.5 so they arent too far off. I wonder what kind of problems it being a little bit off would cause.

Armando,

[JasonC]

What are the t count your using or want. I have a extra set.

Jason