I recently purchased Ivan Law's book on gear cutting. In making the button tool to form the gear cutter he shows a table that lists the various dimensions for the button tool that forms the different gear cutters. I have a bull gear on a 1/3 scale steam engines that specifies a 16" pitch diameter and 96 teeth. According to the book that would be a #2 gear cutter with a diametral pitch of 6. According to the table that woulod take a button 5.35" diameter and a spacing of 5.26" center to center. Am I reading something wrong. Those dimensions would be very difficult to work with the way they are presented. Or does this method only work on very small gears. Is there some other method of creating a forming tool for these larger gears?
gear cutting questions
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Read the paragraph just above the table
Those sizes are for 1DP, you need to divide the sizes by your chosen DP so in your case that is 6 so your buttons will be 0.892" dia
J
Those sizes are for 1DP, you need to divide the sizes by your chosen DP so in your case that is 6 so your buttons will be 0.892" dia
J
Sorry, I often see the same question where people don't read the bit above but you had already divided by 6 and I divided that again, should have got the book out and checked.
You don't really need a whole circular button to cut the tool, if you can mount say a 1/2" lathe tool so it can be swung at the correct radius against a grind stone that will give you the correct curve of the tool. Or mount a silver steel bar in the lathe so the end can be cut to the 5.35 radius.
Its then just a case of mounting the tool in the correct relation to the cutter blank so you cut the right depth and spacing of the two curves.
As the cutters DP gets larger this method is not so practical but gear cutters are not that expensive so less hastle to buy them.
You don't really need a whole circular button to cut the tool, if you can mount say a 1/2" lathe tool so it can be swung at the correct radius against a grind stone that will give you the correct curve of the tool. Or mount a silver steel bar in the lathe so the end can be cut to the 5.35 radius.
Its then just a case of mounting the tool in the correct relation to the cutter blank so you cut the right depth and spacing of the two curves.
As the cutters DP gets larger this method is not so practical but gear cutters are not that expensive so less hastle to buy them.
Yes provided your blank is the correct dia you touch the edge and then set your depth of cut from there. generally do it in one pass if your machine is upto it.
Had another thought about making the cutters, if you have a ball turner that will do concave then that will be easy to set up to do the 5.35 dia a bit like this
Had another thought about making the cutters, if you have a ball turner that will do concave then that will be easy to set up to do the 5.35 dia a bit like this
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I gave up making DIY Gear Cutters. These are so good and cheap from CTC.
I bought Model 0.8 and 1.0 to cut timing gears. Each Module came with 8 cutters from no.1-------8. Webster, Rupnow and Nemett-Lynx Engines ran with DIY Timing Gears. Cut Mitre Gears too.
I bought Model 0.8 and 1.0 to cut timing gears. Each Module came with 8 cutters from no.1-------8. Webster, Rupnow and Nemett-Lynx Engines ran with DIY Timing Gears. Cut Mitre Gears too.
Gus
I have come to the same conclusion on diy gear cutters. I have a ball turner but the hassle of setting it up to get the right radius and then not knowing how well it would work in cutting such a large radius on the cutter blank. Then heat treating it. Then after all that not knowing how well it would work in actually cutting the gear. This is probably a five year project. Diy gear cutters could add another year or so. I'm 67 years old. I may not live long enough to see this thing up and running. I have been doing some researce (Machinery Handook, utube's lazy machinist and Ivan Law's book) and I have figured out most of the depth of cut. One problem I have is with the constant used in figuring out the whole depth. The lazy machinist used 2.2 divided by diametrical pitch plus .002. This is for a 14t 14 pitch gear. My gear is 96t 6 pitch. I see another formula in the Machinist Handbook that uses 2.157 divided by the diametrical pitch. Which one do I use? Boston gear shows the 2.157 for gears coarser than 20 pitch. This lazy machinist video showed the 2.2÷dp-.002 for a 14 pitch tooth. Which formula do I use for a 6 pitch gear?
I have come to the same conclusion on diy gear cutters. I have a ball turner but the hassle of setting it up to get the right radius and then not knowing how well it would work in cutting such a large radius on the cutter blank. Then heat treating it. Then after all that not knowing how well it would work in actually cutting the gear. This is probably a five year project. Diy gear cutters could add another year or so. I'm 67 years old. I may not live long enough to see this thing up and running. I have been doing some researce (Machinery Handook, utube's lazy machinist and Ivan Law's book) and I have figured out most of the depth of cut. One problem I have is with the constant used in figuring out the whole depth. The lazy machinist used 2.2 divided by diametrical pitch plus .002. This is for a 14t 14 pitch gear. My gear is 96t 6 pitch. I see another formula in the Machinist Handbook that uses 2.157 divided by the diametrical pitch. Which one do I use? Boston gear shows the 2.157 for gears coarser than 20 pitch. This lazy machinist video showed the 2.2÷dp-.002 for a 14 pitch tooth. Which formula do I use for a 6 pitch gear?
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I am 71 and hopefully keeping my mind,body and hands busy,I can have another 3-----5-----8 years more to tinker around in the balcony machineshop.
Found an easy out ,got hold of Japanese KG Gear Master Catalogue which gave me all the data. From here I get O.D. and tooth height and gear cutting can be done. Like you ,I am so familiar with Imperial Module Gears. But when it comes to theory and calculations I got lost. With the KG Calalogue,I have cut a dozen of spur gears. Also have a good collection of gears with 1/2 tooth more or less to keep as paper weights. Went on to cut mitre gears too.
For starters, use aluminium and then brass to practice. The CTC Gear Cutters,I suspect will require cutting copious fluid for long life.
Gear cutting is different ball game from turning and milling. To make it simple,I use direct index as per Harold Hall's.
Took a few bad gears before good gears happened. The HMEM Gear Cutting Members will vouch on this.
