Photos of gear cutter form tool.

[raynerd]

Hi,
I`m sorry for the questions, I`ve got a few things going at the same time - all based on the same engine/build.

I`ve cut a few gears now for clocks (wheels) and my last attempt with Stew was succesful. I will continue with this method of wheel cutting when I resume my clock build...when that may be! However, I`m now after cutting a spur gear and I`m really happy now, after much headache, about how I will cut the gear. I`m going to use the calculations in John Stevensons article to make my cutter to get the correct profile. I`m actually all ready to go, I`m just not absolutely clear about how to make the cutter profiling tool.

I can see all the measurements, I`m just not clear how to mount the buttons. Again, I can see from John`s article it is using grub screws but I think a picture would be helpful just to clarify! Is the distance between buttons adjustable or does the bore for the buttons just have to be cut accurately so that they are the correct distance apart.

Does anyone have a picture of a gear cutter profiling tool? Just to be clear, I`m not asking for the gear cutter itself or even the profile of the cutter, I`m just confused about the tool for holding the pins/buttons to offer upto the gear cutter blank.

John article...
http://www.metalwebnews.com/howto/gear/gear1.html

Any help very much appreciated.
Chris

[Pete.]

I can answer that because it's very simple, and because I just spend two days cutting my own first ever gear.

Once you work out the size of the buttons you need, and the distance apart, using the info from that page all you do is take a piece of flat plate and cut a slot in the end just wider than the gear cutter that you are making, and deeper than the tooth depth. Any old scrap plate will do, just make it thick enough so it won't bend.

[raynerd]

Pete, I thought that was the case but by any chance any photos???

I get the impression the buttons go in at an angle to get the correct front relief?

[Pete.]

Got no photos becauseI didn't use the button method, but I did a drawing if it helps.

White is the mounting plate, blue the buttons and the red line is where you machine the buttons down as mounted on the plate.

[raynerd]

AHHHHhhhhhhhh!!! 

Buttons!!


Now it all makes sense. So there is only a small width of full diameter (button), the diameter is then taken down to a smaller dia to put through and fasten to the plate.

Cheers Pete!

[Pete.]

If you have a mill & boring head you could use the method I used, since I didn't have large enough material for buttons.

http://bbs.homeshopmachinist.net/showthread.php?t=45649

[raynerd]

Hi Peter, excellent work on cutting the gear. I`ve used a single point cutter in the past on a clock wheel and I didn`t find it great. You have obviously done a good job but I like the idea of profiling the cutter in one shot, using this tool John describes. I fancy giving it a go but clearly single point cutters can be used with success.

I`m just making a little boring bar setting device at present, then I`m going to jump to gear cutting. I`ll let you know how it goes.

[around]

Chris,

I just finished cutting two bevel gears to repair a friend's radial arm saw.  Pictures of the tools and gear attached.

Cheers,

Adrian

[raynerd]

Fantastic !!!  

That is mighty helpful! I`ll hopefully make it in the next couple of weeks. I have done on the calculations based on John Stevensons tables and the only thing that confuses me is the infeed. I know in Ivan`s Workshop Practice series gear cutting book,  his numbers are different but my understanding is that Ivan touches the centre of the front leading edge of the profiling tool on the front edge of the cutter blank, moves to the side and then infeeds. So a lot of the start of the feed is a blank cut in air. Am I correct that when using the this method. The centre of the profiling tool is centered with the middle of the cutter blank, moved in until either edge of the buttons are just touching both sides of the cutter blank and the "feed" is measured from that position?

Once again, thanks for the pictures. Very much appreciated.

Chris

[around]

Chris,

Your description of the operation is correct.  The in-feed tables in Ivan's book assume that the feed is measured from the most forward edge of the cutting buttons.  As you described, I touch the leading edge of one of the buttons to the end of the tool blank, reposition the tool blank between the buttons and proceed with the cut.

Drawings of the 16DP #6 cutter used to cut the bevel gear attached.

Cheers,

Adrian

[Lew_Merrick_PE]

John Stevenson's approach is rather interesting.  The diameter, angle, and spacing of the "pins" create nominally elliptical forms to approximate the involute.  While an AGMA inspector would be horrified, it ought to create reasonably good gearing.  I will have to think on it.  Anyone playing with gears really ought to get a copy of the Stock Drive Products -- Sterling Instruments (SDP/SI) Handbook of Gears at http://www.sdp-si.com/.

[RichardShute]

John Stevenson's approach is rather interesting.  The diameter, angle, and spacing of the "pins" create nominally elliptical forms to approximate the involute.  While an AGMA inspector would be horrified, it ought to create reasonably good gearing.   

Lew,
have a look at this thread, it's an excellent description of the scheme:
http://bbs.homeshopmachinist.net/showthread.php?t=41591

John Stevenson's drawings for comparison with a true involute assume a circular button profile and the error is remarkably small. Arithmetically, you are quite correct regarding the elipse, but the eccentricity goes 'the wrong way' so slightly diminishes the accuracy rather than improving it. That said Cos (clearance angle) is so near to 1 as to be of no practical consequence.

Richard

[raynerd]

  I can`t imagine a AGMA inspector will be checking my Webster IC engine 

[Rob.Wilson]

Hi Chris


I have made a good few gear cutters using the button method , single  and multi toothed ,, easy to do  and CHEAP    most of all FUN  





Rob

Here is a gear chart that may come in handy .. i keep it handy in the shop .




http://www.mediafire.com/file/grnityxwny0/Technical%20data%20sheet%20gears....pdf

[raynerd]

Rob, really sorry, I totally missed this post which is why I never replied!

Thanks for the images, you have totally made my night!! I have just got back from the workshop gutted, thinking that my buttons looked too close and I`d mucked up the calculation, but looking at your far right image I think I`m OK! I`ll harden the buttons tomorrow and then will hopefully have a go cutting later in the week.

What is the object far left?

Chris

[Bryan]

What is the object far left?

Chris

That looks like the form relieving tool described by Ivan Law in his Workshop Practice book "Gears and Gear Cutting". I just got my copy the other day. I haven't read that section yet, but I have read a fair bit of the book and I would encourage anyone interested in making gears to get a copy. I'm not universally enthusiastic about the Workshop Practice series, but this one's a cracker. Law can write for starters. He very simply and clearly demystifies the geometry. I couldn't put it down actually.

[Rob.Wilson]

Hi Chris

I am pleased the photos helped    ,good look making the cutters  ,,, The doodad on the right is as Bryan replied    


Rob

[John Stevenson]

Same as Bryan says about Gears and Gearcutting by Ivan Law, I have literally 8 foot of shelf space given over to gear books and manuals, it's a hobby of mine, yes I know sad bastard etc,.

Ivan book is my favourite bar none because it cuts out loads of mathematical calculations that you have no control over or they don't matter anyway. It is the simplest of books on the subject that cover all the home shop guy needs and nothing more.

It must be good as Rob Wilson says he can understand it so that saying something, I think he has one of the later copies that has been translated into Geordie.

John S.