I'm going to make a dummy (major spline inside diameter) in ali, 20 deg, see how it rolls with the 38 tooth gear I have. I'm very convinced it isn't 14.5 deg.Nah that gear is definitely a 12DP
I'm going to make a dummy (major spline inside diameter) in ali, 20 deg, see how it rolls with the 38 tooth gear I have. I'm very convinced it isn't 14.5 deg.Nah that gear is definitely a 12DP
Aw poo, just made and mounted an identically sized blank...Remember that for low tooth counts it's normal for the blank to be over-sized:
View attachment 332543
So increase your theoretical blank size by 62 thou and you'll probably find that not only does the negagement improve but the tooth form will also.
Remember that for low tooth counts it's normal for the blank to be over-sized:
Please take note of the title of the table "enlarged pinion and reduced gear dimensions". So it refers to altering both items of a PAIR of gears.
Making just the pinion bigger without making the gear smaller will change the centre distance. In the photos the OP has shown, altering the centre distance does not appear to be possible.
Consider also how the table mentions a minimum number of teeth for the gear that mates with the pinion. His 38t gear is less than the 44t in the table so the pinion needs to be undercut.
There is no way to produce undercut with a form cutter so you have to mimic it by leaving skinny teeth. If the teeth on the pinion are too thick, the tips of the gear, instead of going into the space where the undercut would be, will hit metal (you can blue up the pinion to check its contact patch).
Yes, I would agree it feels a little loose.That's right but you only have to do that when the centre distances are fixed. If the pinion is made large and the centre distance increased to allow for it then the gear can stay standard and we know that it is because it's right there with measurements. Just going by the image the engagement looks very loose.
Well I did some research. It seems that for the cutter I tried, P&G 12DP No6. The company that makes them has a range thus:Well so far I only have one gear...
Think I'll try my cutter to see what it looks like, chances are though it's 20'degree, and I don't have one of them.
Or do I?
Here's a question for the knowledgable, what I've noticed going through all these cutters is that not all list the tooth number range, just the cutter number. Is there a given range of tooth count to cutter number - maybe for each manufacturer? Or a standard? Or do I need to find each manufacturers data to find the corresponding range to tooth count? Sheesh, I hope not...
That's interesting they number the metric (MOD) cutters differently.Well I did some research. It seems that for the cutter I tried, P&G 12DP No6. The company that makes them has a range thus:
View attachment 332598View attachment 332599
Why make it simpleYep module cutters are often numbered in reverse.
Thanks, will have a lookBut late now but Andy's Machines did a nice video on identifying gears...