Anyone gear cut a pinion?

[gaz1]

Thanks @gaz1 you missed the point that its a helical. Thanks anyway...

thats done on your milling table by either using angle iron to create the cross cut or a universal table that rotates round so you can do the diagonal cross cut on the steel bar

you can do it with long bars that way as your only milling in the middle

 

[minimutly]

thats done on your milling table by either using angle iron to create the cross cut or a universal table that rotates round so you can do the diagonal cross cut on the steel bar

you can do it with long bars that way as your only milling in the middle

Yes, you can cut a rack that way, but not a pinion. I'm just starting out with this so any suggestions appreciated.
Thanks.

 

[Pete.]

thats done on your milling table by either using angle iron to create the cross cut or a universal table that rotates round so you can do the diagonal cross cut on the steel bar

you can do it with long bars that way as your only milling in the middle

You can't cut a pinion that way the part has to turn as it travels through the cut.

 

[addjunkie]

Yes, you can cut a rack that way, but not a pinion. I'm just starting out with this so any suggestions appreciated.
Thanks.

Universal dividing head or cnc is the only way I know!

Id buy in plenty stock for the practice attempts!

 

[minimutly]

Universal dividing head or cnc is the only way I know!

Id buy in plenty stock for the practice attempts!

Plastic...

 

[minimutly]

Happy as a dog with two dicks today. Everything has come together, well nearly. Looks like I might need an extra idler pin? Or maybe not..

 

[Agroshield]

What you have is the same as the B&W image. Gear on the leadscrew. Gear on the dividing head. Two gears in between. The gear carriers should be long enough to accommodate two gears stacked, with a spacer if only one gear is needed. Similarly on the leadscrew and head - one gear and one spacer, with the order swapped depending if the gear is inboard or outboard.

 

[minimutly]

So, I need to work out the lead (from the pinion or the rack I guess - or will any out of square between the two throw that out? might be harder than it seems to measure..) Maybe in this case the leads will be different?
Then from Machineries handbook work out the gear train, tilt the bed, stick some appropriate dia stock in there and try it. I don't have the right cutter yet, but hopefully its not a special...
Would help if Mrs mm didn’t want to drag me away every opportunity...

 

[Misterg]

So, I need to work out the lead (from the pinion or the rack I guess

As I understand it:

You need to measure the helix angle (should be much easier from the rack than the pinion) and calculate the gearing between the rotary head and the table depending on the PCD of the gear you're going to cut:

For one rotation of the rotary head, the X axis must move by:

X= (pi x PCD )/ Tan (helix angle)

(from the last page of the PDF in my previous post)

(edit: And it needs to be in the correct direction to suit the 'hand' of your helix.)

 

[minimutly]

Made some progress on this today:-
Damn, didn't take a pic, wait a sec.

 

[minimutly]

Made some progress on this today:-
Damn, didn't take a pic, wait a sec.View attachment 404831

So the one I want to copy (actually, for a nearly first attempt, in alu, with the nearest but not correct cutter it wasn't so bad, but).

Anyone spot the obvious mistake?

 

[mtt.tr]

So the one I want to copy (actually, for a nearly first attempt, in alu, with the nearest but not correct cutter it wasn't so bad, but).
View attachment 404832
Anyone spot the obvious mistake?

Holy notifications batman!!!

 

[minimutly]

Holy notifications batman!!!

Well I know its been a while....

 

[minimutly]

Anyway, classic error, I cut the helix the wrong way...
Simple to fix error thought I, tilt the bed the other way, turn the cutter round and run it backwards?
But it's not. The gear train from the bed tomthe dividing head needs reversing, and right now I can't do,it. It needs an extra gear in there - the issue being I've allready added an idler to make up the distance, so now I need two identical idlers, which means I need to make a gear - but at least it's a simple spur..

 

[fizzy]

Definite progress well done. Always wanted to cut gears not tried yet.

 

[Pete.]

Anyway, classic error, I cut the helix the wrong way...
Simple to fix error thought I, tilt the bed the other way, turn the cutter round and run it backwards?
But it's not. The gear train from the bed tomthe dividing head needs reversing, and right now I can't do,it. It needs an extra gear in there - the issue being I've allready added an idler to make up the distance, so now I need two identical idlers, which means I need to make a gear - but at least it's a simple spur..

I spotted it right away but only this morning I was pushing out z's early last night.

BTW you don't need an identical idler unless there's space constraints. As an idler it can be any tooth count.

 

[minimutly]

I spotted it right away but only this morning I was pushing out z's early last night.

BTW you don't need an identical idler unless there's space constraints. As an idler it can be any tooth count.

I've allready inserted one idler to make up the distance, my head tells me another one of differing tooth count will change the gearing - hence the need for two identical idlers. Am I wrong here?
I've piggy backed (there must be an engineering term for this?) the second and third gears, so if I unstack the third gear and put it in line, keep my idler, it will maintain the ratio and reverse direction? Which means I just need to make a new spindle... as long as they all fit on the banjo, I think...

 

[paradipiro]

I've allready inserted one idler to make up the distance, my head tells me another one of differing tooth count will change the gearing - hence the need for two identical idlers. Am I wrong here?

The idler is not changing the ratio, only rewerses the direction. It can be any available toothed gear, what takes the space.

 

[minimutly]

The idler is not changing the ratio, only rewerses the direction. It can be any available toothed gear, what takes the space.

Yes I worked that out. But if I add another idler of a dirfferent tooth count it will change the ratio? Won't it?

 

[paradipiro]

Yes I worked that out. But if I add another idler of a dirfferent tooth count it will change the ratio? Won't it?

No, it will not change the ratio. The idler itself will rotate at a different speed, but at the end of the gearchain, the ratio will be the same.