NYLON MILLING MACHINE GEARS

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Brian Rupnow

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I have a little story to tell. I have a CX601 milling machine from Busy Bee Tools and I love it. This milling machine does everything I want, except drill 1" holes in aluminum. I don't do that very often, but when I do, it's mostly ornamental holes thru flywheel webs. And this is the point where my mill lets me down. There is a nylon compound gear in the gear-head, and it lets you put the mill into the equivalent of "back-gear" on a lathe. About every two or three years, this compound nylon gear manages to strip all the teeth of one side. It costs around $70 for a new gear, and it's a royal pain to take the mill apart and replace the bad gear. It doesn't happen all at once. When it first decides to eat that gear, it jumps out of gear into neutral. If you can spare a hand to hold it in gear, it works just fine, but sometimes I run out of hands to do that. It doesn't take much force to hold it in gear, and I'm sure that if it was held firmly in gear so that it couldn't jump out, then it wouldn't wreck the gear. So, today I'm designing a third hand to hold the mill in "back gear" while I drill large holes. In the pictures, you will see a side view of my mill where the gear selector knob is, another picture that shows my "third hand" in position, and in the third picture you can see a bad nylon gear and it's replacement good nylon gear.
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Brian Rupnow

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And here you can see a 3D model of my milling machine with the knew "third hand" installed and a detail of the 3/4" thick third hand. The 1/2" diameter knurled steel pin screws thru the arm and is captured behind the sheet metal enclosure that houses the motor. This sheet metal housing is quite "beefy" and should easily be able to counteract any forces that try to shift the gear selector out of gear. To put the machine into it's normal gear, you just unscrew the threaded pin enough that it no longer is held captive behind the steel motor housing.
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RonGinger

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Grind a fly cutter bit to the shape you need. Then cut metal gears. If you don't have an index head use the plastic gear as a guide.
 

johwen

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I have the same Mill here in Australia Original lasted about two years and then stripped likewise the second did the same. I haven't bothered replacing same for two years now I just use the mill on high gear. I have thought of making a metal gear next time but would have to remove the gear and assemble head to make the gear and then dismantle again to to put in the new gear. Maybe I could ask you if you could give me the OD of the gear and Number of teeth and pressure angle I could make same before I strip the box down. Also the thickness. I would appreciate your help if you would. The mill does a great job and is quite accurate. My mill is brand name WEISS Machinery Co. LTD Thank You John
 
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I have the same mill, also in Oz, branded Optimum, it has metal gears in that position. The only problem I've had is a motor controller failing but that was easily replaced. I suspect the gears are module 1.
Cheers, Fred.
 

Carbuilder

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Simple but very cool solution. As to making a metal gear to replace the nylon one...well...the nylon one seems to be the weak link now. If you replace it with something stronger, maybe you find the next weak link and it could be something more serious?
 

Bentwings

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Why not make a replacement aluminum gear? It looks like a pair of pinned-together spur gears would do the trick. - Terry’s was going to suggest the sam thing. Doing som internet shopping you may be able to come up with the right gears and just pin them together. A couple of dowel pins to positive locate them then maybe some small flat head screws to more or less permanent hold them together. A long time ago I repaired a tool room lathe this way it worked perfectly untill one of the guys insisted on making a rediculously large part with heavy interrupted cut. It finally broke the spindle shaft. Which turned out to be unobtanium so we had to make a new one . I think each one of us in the tool room had a hand in making the new one . That old lathe is still running as far as I know. Wish it was mine.
Good luck

byron
 

Brian Rupnow

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My mill was made in China, so odds are pretty good that the gears are metric. I can put up a drawing with all the dimensions. I have only 24DP gear cutters, and don't want to fool around trying to make a single point cutter to match these gears.
 

Bentwings

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My mill was made in China, so odds are pretty good that the gears are metric. I can put up a drawing with all the dimensions. I have only 24DP gear cutters, and don't want to fool around trying to make a single point cutter to match these gears.
There are man site devoted to gear both metal and plastic
McMaster Carr has gears bu they are rather expensive . You could get exactly why you need . I buy odds and end from them. Very good service fast shipping
Byron
 

Brian Rupnow

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This is the shape of the nylon gear I currently have. The tooth form is an approximation
The gears are measured with a Vernier caliper.
xtX4Lr.jpg
 

Jasonb

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They are MOD 1.5 20deg pa
 

Brian Rupnow

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All right!!! You fellows have convinced me. Time to make a raid on the Rupnow Fortune and buy Three annular cutters, a 1", a 15/16" and a 7/8". These things come with a 3/4" shank, and I don't have any R8 collets that are big enough, so I will buy 3 dedicated R8 collets which will take a tool with a 3/4" shank. I will still go ahead and fabricate the aluminum arm which will prevent the mill from jumping out of gear when in low range under heavy load. Thank you for your help.---Brian
 

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Bentwings

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This is the shape of the nylon gear I currently have. The tooth form is an approximation
The gears are measured with a Vernier caliper.
xtX4Lr.jpg
McMaster Carr has plastic gea 56 an 30 tooth metric

ye cheap probably ost more for postage
I just got some I ordered based on bill of Métis from another site. Wrong size so I’ll let you chose based on your measurements I think you could pin and use flat head screws o hold them together

I’m working on a transmission with. Cluster gear so that’s what I’ll do. You can get just about any screw o fastener from hem. Micro fastens has even smaller fasteners need. I’ve bough hundreds of screws and fastened over years from both. We have some grizzly machines so we get stuff from hem too. Sometimes they ship good some times it takes for be our rotary table has been on order and paid for over 3 months now I could really use it shortly

grainger is another supplier we purchase from they have been pretty good too.
 

Ghosty

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McMaster Carr has plastic gea 56 an 30 tooth metric

ye cheap probably ost more for postage
I just got some I ordered based on bill of Métis from another site. Wrong size so I’ll let you chose based on your measurements I think you could pin and use flat head screws o hold them together

I’m working on a transmission with. Cluster gear so that’s what I’ll do. You can get just about any screw o fastener from hem. Micro fastens has even smaller fasteners need. I’ve bough hundreds of screws and fastened over years from both. We have some grizzly machines so we get stuff from hem too. Sometimes they ship good some times it takes for be our rotary table has been on order and paid for over 3 months now I could really use it shortly

grainger is another supplier we purchase from they have been pretty good too.
McMaster don't post out of the USA, have tried, so has Brian.
Cheers

Andrew
 
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