King 1440 and Craftex Threading

[John Conroy]

I used the same formulae as you did along with this chart published by Evolvent Design. There is a short video from them also that gave me more confidence in deciding it was M1.25 ( I know you hate YouTube vids but it may help someone else.) I decided on a 20 degree pressure angle because I couldn't find any information about any other angles being used for M1.25 gear teeth. I went through the selection for M1.25 gears from Maedler North America (these guys sell all kinds of cool stuff) and there is no mention of any angle other than 20 degrees.

Spur Gears, Steel, Module 1.25, Tooth Width 10 mm, With Hub – Maedler North America

maedlernorthamerica.com

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[Susquatch]

I decided on a 20 degree pressure angle because I couldn't find any information about any other angles being used for M1.25 gear teeth.

Now that's what I call practical...... Wish I had thought of that one!

Thanks John!

Ps - don't forget to vote on the special member motion under section 42 of the bylaws of the CHMW forum.

Metal gauge?

I was referring to her obvious appreciation of weatherproof vehicle compartments. .....which is important when you are pursuing that enviable " Paridise by the dashboard lights".....:rolleyes:

canadianhobbymetalworkers.com

 

[John Conroy]

If you're planning on making a M1.25 gear between 35 and 54 teeth I could send you the cutter and arbor.

 

[Susquatch]

If you're planning on making a M1.25 gear between 35 and 54 teeth I could send you the cutter and arbor.

That is a very generous offer. I might take you up on it. But before I put you to that trouble I'm gunna try and get a whole set on Ali or Bangood so I can cut any gear I want.

 

[DPittman]

I'm pretty sure my gears are module 1.25 too. It's either that or 20 DP. The measurements and numbers don't work out perfect for imperial. I'll prolly go with 1.25 because my lathe was made In China. The gear bore is 1" though so...... Yet another hybrid.

My question is, how did you determine you needed a 20° pressure angle? I can see no visual difference to help me determine this.

All the previous gear cutting I have done was on much bigger gears. This little stuff is bewildering to me. I'm no watch maker. Even under a Magnifier it isn't clear to me what they are.

The best I could come up was this. It's a 40° gauge. I used the biggest gear I have to get as close to a rack as possible. It was hard to take a photo under a magnifying glass, so it's not a perfect picture, but you get the idea.

The math on that particular gear is 78 teeth OD is 3.933" or 99.89mm

(78 + 2) / 3.933 OD = 20.34
Call it 20

99.89 / (78 + 2) = 1.249
(call it 1.25)

Here the app info I use for gear cutting...

 

[Susquatch]

Here is the app info I use for gear cutting.

I cant seem to find the website or the app. Is it perhaps Apple oriented?

And how does it help you identify a particular pressure angle?

 

[DPittman]

I cant seem to find the website or the app. Is it perhaps Apple oriented?

And how does it help you identify a particular pressure angle?

Sorry I wasn't very clear on what info I was offering.

No the app is for android not Apple, I wouldn't be surprised if Apple has a version available also, although when I go to Google Play store it says it was made for an older version of Android than mine, although it's working fine for me. Maybe its a defunct app now?
.
Although the info does not show pressure angle, it shows all other relevant gear cutting info.

 

[Susquatch]

No the app is for android not Apple,

OK, Android is good. But I couldn't find it. What is the name of the app as it appears in the app list (which can be different than its screen name).

 

[DPittman]

OK, Android is good. But I couldn't find it. What is the name of the app as it appears in the app list (which can be different than its screen name).

I'll be damned if I can find the app now on Google Play. I have it on my device and it works. I was going to send you some sort of link to it but I can't even find it in my list of apps?!

My brain is cooked tonight (more than usual). Maybe tommorow I might be able to offer some info of some use.

 

[Susquatch]

My brain is cooked tonight (more than usual). Maybe tommorow I might be able to offer some info of some use.

I know the feeling!

I appreciate your efforts very much.

In the meantime, on a pure hunch, I came up with a way of measuring the pressure angle of an involute gear. It requires an angle gauge (which you can make if you don't have one) and the biggest gear you have. Here is a photo. I got the idea when I noticed a set of gear gauges that look a lot like thread gauges. Then I realized I could prolly just measure the angle on a gear with a high number of teeth by comparing it to a known standard. The photo is taken through a magnifying glass.

When the gear is big, the gear sides become straight instead of following the typical involute curve. As a result, it possible to use a 40 degree angle gauge to validate a 20 degree pressure angle (see photo). I don't have a photo for a 30 degree gauge, (closest I have to 16.5x2) but it was obvious that it is not right.

Since I was sulking most of the day about not being able to join any meetups, I went shopping instead. That seems to work well for my wife and I confess it helped me too. I just wish I could found something reasonable in canada. I ordered a full set of modulus 1.25, 20 degree gear cutters from Ali. I also ordered an R8 Gear Cutter Arbour. Both were free shipping.

 

[Susquatch]

Hey @John Conroy - another question.

You used bar stock to make your gear.

I'm thinking of using plate instead. Either way, there will be a lot of scrap, but I think it's easier to source plate than bar. I can rough cut on the band saw and maybe use old bolts for a two piece shoulder. Either way, I need to cut a keyway. How did you do that? Did you use a broach (which I don't have) or do you know of a decent kludge for cutting a keyway?

 

[140mower]

Hey @John Conroy - another question.

You used bar stock to make your gear.

I'm thinking of using plate instead. Either way, there will be a lot of scrap, but I think it's easier to source plate than bar. I can rough cut on the band saw and maybe use old bolts for a two piece shoulder. Either way, I need to cut a keyway. How did you do that? Did you use a broach (which I don't have) or do you know of a decent kludge for cutting a keyway?

I have cut several on my lathe and one on the little mill/drill. I wouldn't want to make a career doing them that way, but for a one off.....

 

[John Conroy]

I posted about turning the gear blanks in post # 120. I ground a 5mm HSS cutter for my 5/8" boring bar and mounted it in the tool post then plunged through the bore by moving the carriage along it's long axis. I advanced the cross slide in .0005" increments for each plunge through the gear blank. Long and tedious but got the job done.

 

[John Conroy]

I have about 6 feet of 4" round 4140 bar stock. If you want a couple of slices of it to make your gears you would only need to pay for the postage. Just let me know how thick each slice should be.

 

[Susquatch]

I posted about turning the gear blanks in post # 120. I ground a 5mm HSS cutter for my 5/8" boring bar and mounted it in the tool post then plunged through the bore by moving the carriage along it's long axis. I advanced the cross slide in .0005" increments for each plunge through the gear blank. Long and tedious but got the job done.

I don't know how I missed that. I read about a similar approach a few years ago but dismissed it as impractical. Your experience tells me otherwise. I am not afraid of long and tedious! I'll give it a try.

If you want a couple of slices of it to make your gears you would only need to pay for the postage. Just let me know how thick each slice should be.

Yes, that is an amazing offer! Thank you John. I'll be in touch shortly!

 

[140mower]

I posted about turning the gear blanks in post # 120. I ground a 5mm HSS cutter for my 5/8" boring bar and mounted it in the tool post then plunged through the bore by moving the carriage along it's long axis. I advanced the cross slide in .0005" increments for each plunge through the gear blank. Long and tedious but got the job done.

This is the approach that I have taken...... In fact, it's the first thing I did on my 10" South Bend, put a keyway into the drive pulley on the motor so I could turn my first piece of metal into scrap.....

 

[Susquatch]

My arbor came a week ago and my cutters were waiting for me when I got back from the wedding we went to on the weekend.

The arbour seems fine.

The cutters are exactly what I expected from Ali. They fit my existing gears perfectly so the advice everyone provided worked great. They will cut new gears but the quality just isn't there. It looks like they were sharpened by hand......

The gears won't go onto the arbour either. The keyway doesn't fit the arbour real well. I'll either grind the key a bit on the surface grinder or just polish it by hand till it fits.

For the money and how often I'll use them, I can't really complain too much.