Milling Rite

[Ischgl99]

This looks like a possibility, they say they do made to order gears as well, might be worth calling up their applications engineers and seeing if they can find something that fits, and if not, what it would cost to make a set for you. You can also call up DC Morrison and ask them if they can tell you where they got the gears for the mill, since they are no longer selling Burke parts, they might tell you, or might even have the specs for the gears instead of having to guess.

Linn Gear Co.

Linn Gear manufactures stock and custom sprockets, gears and other mechanical power transmission components for industrial applications.

www.linngear.com

Since you are replacing both gears, and will likely need to modify them in some way, I was going to suggest metric gears, but it looks like the metric sizes are not close enough to what was in there. For metric gears, I use Maedler North America, attached is the product page for bevel gears with a 2:1 ratio, the module 2 in a 15/30 gear pair is a bit smaller than you need, and the M2.5 is bigger, so might not fit. I couldn't find any metric gear suppliers that make other than a 15/30 gear set in that size, but if you can find someone that makes 16/32 or 17/34, then it might be a good size fit.

www.maedlernorthamerica.com

 

[Dave Bonzo]

Those are good suggestions; I'll send some emails with pictures/numbers to start, and then move to phone calls as needed.

Also - and this is me not understanding gears - do I have to replace them both? Is it possible to put in, say, a 48-toorh gear as a replacement for the 32 and leave the 16-tooth in place? I'd have to adjust the spacing on the 16 by moving it back, but as long as the rest of the numbers worked, shouldn't they interchange?

For reference: I do plan on either replacing both gears or trying to repair this one...i just don't know about trying to braze teeth that small and then hand-file them into a correct profile. This doesn't feel like one of those times when close is good enough: I've had a few ring and pinion sets drill that lesson into my otherwise-thick skull.

 

[Dave Bonzo]

For metric gears, I use Maedler North America, attached is the product page for bevel gears with a 2:1 ratio, the module 2 in a 15/30 gear pair is a bit smaller than you need, and the M2.5 is bigger, so might not fit.

I'll have to look at the dimensions and convert them into Freedom Units before I can comprehend things - being a dinosaur is fun, but it comes with having a very small brain - but as a theoretical question: if the module 2 is a bit smaller, could I not space each of them to the correct position and either drill or bush the bores to the correct size? My dinosaurus-brain was interpreting the prior suggestions regarding modification into something like that; I'd have to shim the larger one upwards or replace the thrust bearing that it rides on, and I'd have to do the same kind of thing on the smaller gear by changing the position of the shaft, but as long as they're within the mounting depth envelope it should work...right?

 

[Ischgl99]

You have to replace both, you can’t put in a gear with a different diametral pitch, the teeth won’t match up. A 48 tooth gear in the same pitch would be significantly larger than what you have now, so to fit a higher tooth count gear would mean the DP would have to change to a finer pitch, and that would mean weaker teeth. A new gear may use a different contact angle as well from the old one, so that adds another complication to it.

With the module 2 gears, you should be able to put a spacer in there, or the gears may already be longer than what you need and you can trim the gear hub. The danger is the teeth may not be strong enough to carry the weight of the knee and whatever you put on it. I don’t know what the load capacity of a DP12 gear is compared to the mod2, but it appears the sizes are relatively close enough that it won’t cause an issue for most hobby machining activities.

I just had a thought, I wonder what a Bridgeport uses? Those parts would be easier to find, and might be close enough for you to use.

 

[Dave Bonzo]

You have to replace both, you can’t put in a gear with a different diametral pitch, the teeth won’t match up. A 48 tooth gear in the same pitch would be significantly larger than what you have now, so to fit a higher tooth count gear would mean the DP would have to change to a finer pitch, and that would mean weaker teeth. A new gear may use a different contact angle as well from the old one, so that adds another complication to it.

Okay, that makes sense...I think. Thank you!

With the module 2 gears, you should be able to put a spacer in there, or the gears may already be longer than what you need and you can trim the gear hub. The danger is the teeth may not be strong enough to carry the weight of the knee and whatever you put on it.

I've seen a modification to the knee that addresses this idea: gas struts that push some of the load up and off of the gear set. I'm not sure how I feel about that to be honest, but it's a solid concept...but by the time I buy a pair of gears and then install a set of gas struts, I could have just retrofitted a set of linear actuators to the knee/base and created a power elevator. ‍

I don’t know what the load capacity of a DP12 gear is compared to the mod2, but it appears the sizes are relatively close enough that it won’t cause an issue for most hobby machining activities.

Could I reduce the load by locking the elevation screws and then backing off on the gear just a fraction? Kind of like setting the parking brake before shifting into Park?

I just had a thought, I wonder what a Bridgeport uses? Those parts would be easier to find, and might be close enough for you to use.

They're definitely easier to find; I just looked them up and found several options. I didn't find measurements yet, but the small gear is an 18-tooth and has a keyed shaft, so I know there's a difference...which makes sense.

 

[Dave Bonzo]

Okay...several emails sent; I'll see if anyone responds. In the meantime: the module 2 15/30 gears are definitely different, but maybe I could turn the 15 down to the correct height and use a spacer on the 30 - again, per suggestion - and then bore both as needed? I guess I need to get this lathe I have in service at some point; might as well be now...

 

[RaisedByWolves]

‍

Did you just assume this machines gender?

 

[Dave Bonzo]

Did you just assume this machines gender?

I saw that the other day; I'm not sure why/how it got added in, but I clipped it back out.

That being said: the machine doesn't have a gender, but it does have a name. It has the most high-maintenance, ponderous and dread-inspiring name I can imagine, as a matter of fact.

Its name is Millicent.

 

[RaisedByWolves]

I saw that the other day; I'm not sure why/how it got added in, but I clipped it back out.

That being said: the machine doesn't have a gender, but it does have a name. It has the most high-maintenance, ponderous and dread-inspiring name I can imagine, as a matter of fact.

It's name is Millicent.

Now you have to get a round of copper and mill out a penny shaped plaque with its name on it.

 

[Dave Bonzo]

Now you have to get a round of copper and mill out a penny shaped plaque with its name on it.

Man, I'm still trying to figure out how to ream a hole in a gear...so: Don't you put that evil on me, Ricky Bobby.