someone to machine brass gear for worm drive gearbox ?

[knighty]

bought a mincer on ebay, advertises as working but needs a re-wire... no problem I thought.. until I stripped it down and found the feed worm gearbox was jammed

stripped it down, looks like water leaked into it, killed the bearings and they've kept using it :-(

I need a brass gear machining for the worm drive... local engineering places I've used before locally have shut down... tried a couple of new ones and they said they couldn't do it and don't know anyone who could (guessing they didn't care enough to think about it)

can anyone here make me one, or tell me where I can have one made ?
(I'm not greedy, happy to pay)

photos...

gear


about 4" across


1" 3/4 thick


shaft it fits onto


worm in gearbox

 

[awemawson]

It'll be bronze not brass, and that is a complex part to machine - it really needs hobbing, which will involve making a hob that mimics the shape of the worm, and gashing cutting flutes in it.

Expect to pay a lot

 

[WorkshopChris]

Expect to pay a lot

As above.

I would look at replacing the whole set up with something off the shelf first, alternatively they will make you a new one from the old bits.
http://www.hpcgears.com/n/products/4.worms_wheels/worms_wheels.php

 

[knighty]

It'll be bronze not brass, and that is a complex part to machine - it really needs hobbing, which will involve making a hob that mimics the shape of the worm, and gashing cutting flutes in it.

Expect to pay a lot

I had my fingers crossed it would be a standard size worm/gear

big mincers are expensive, this one was cheap... expected I'd have to buy a new motor for it so a new gear instead isn't the end of the world

As above.
I would look at replacing the whole set up with something off the shelf first, alternatively they will make you a new one from the old bits.
http://www.hpcgears.com/n/products/4.worms_wheels/worms_wheels.php

guess I could change the worm and the gear?

I'll email that company in the morning :-)

 

[shedfull]

I saved this from another site, not tried it my self yet I need to cut a worm wheel for a saw

rockcampbell

Aluminum

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how to gash it and hob it
Hi,

To do it right you need a hob. Store bought hobs cost a lot. There are a lot of pitches out there, worm sizes, etc. no job shop has it all so here is our workaround for 1 shot gear fabrication in bronze.

You will need a lathe, a bridgeport or equivalent, a dividing head with tailstock, a boring bar that holds a tool bit that will fit the bridgeport, a torch or oven.

To make the hob get a steel you can harden I always go cheap on this cause its a one shot tool. I use 1144 stressproof, easy to cut, gets hard as glass if water quenched from red heat.

The hob will be a shank hob, the shank end fits your bridgeport collet, the worm end will do the work. Turn the worm od .314 x the diametral pitch larger than the existing worm and a inch longer in length than the old worm. Its probably 29 degree single start so grind you up an acme style thread bit to fit the old worm good and chase the threaded section maintaining the root diameter as a tooth thickness control unless you have a set of gear tooth verniers to measure the pitch thickness.

The hob should now look like the old worm on a stick so to speak. Now you have to flute it. put it in an indexer in the bridgeport and set the end mill side on the centerline and cut straight flutes on it, I usually put 3-4 on a 3/4 od worm thread. Remove any burrs but remember these edges are your cutting teeth so NO chamfers just get the hangers off there.

If you used stressproof heat the worm section red and drop straight into a bucket of lukewarm water, NOT COLD WATER, obviously there is a risk here of splashing hot water, shattering steel, etc, etc. Be Cautious if its your first time heat treating. You can always go the high dollar road and use A2 or D2 and air quench if the water quench shakes you up. We just want it hard, how you get there is up to you.

Now for the worm wheel, turn up the blank with provisions for putting it between centers on a pressed in mandrel or built in shank depending on how its made. Get it in the bridgeport, with the indexer set up for the number of teeth. At this stage you could hold the mandrel in a chuck or collet or on centers with a clamped dog.

Take your lathe tool bit from chasing the worm and put it in a boring bar in the mill spindle. Try to get the tip of the tool so it would bore a hole the same size as the hob od, if thats too small of a circle go as small as you can. Tilt the bridgeport head to the helix angle of the worm and gash the teeth as other posts show, 1 pass around, gash depth should be about 1.7-1.9 x diametral pitch to leave stock for the hob.

Now take out the boring bar and put in the shank hob, set your spindle rpm relatively slow 100-200 rpm, put the mill head back vertical. Get the part between centers, no dog, grease on centers, it must turn free but not sloppy. Bring the hob into mesh with the gashed blank with the spindle OFF until there is about .015 slop or clearance. Make sure you start the spindle in the proper direction.

Feed it in slow by hand, there will be a lot going on with the cutter turning and the worm turning and your probably nervous cause its scary looking. The total depth of a standard tooth is like a spur gear 2.157 x dp. Don't be afraid to stop the mill and put the real worm in mesh and measure the center distance, take it out and try it in the saw if you have to, you can always put it back in and shave off some more.

I cut bronze dry or with water soluble coolant if its a big one with more heat. Stress proof steel cutters don't like heat and they are very brittle. Once you learn how to do this a bronze worm gear under 8" od and 1" thick becomes about a 10 hr project if you tinker around with it or about 4 hours if you are in money making mode. I have done and seen done 30-40 of these in my life using this method cause its cheap, effective, and easy. After all laziness is the true mother of invention.

Rock

 

[Pete.]

First thing I'd do is find someone who could cast you a blank or two coz even the stock isn't going to be cheap.

 

[shedfull]

Ive got one of these in the spare room, I just need a metric week

 

[Rig Pig]

Try HPC gears

 

[Shox Dr]

Thought I'd seen something like it.





This ones had it, but they are replaced on a regular basis.

If you want I could make some enquires

 

[ukracer]

I saved this from another site, not tried it my self yet I need to cut a worm wheel for a saw

rockcampbell

Aluminum

Join Date
Dec 2002
Location
kentucky
Posts
106
Post Thanks / Like
Likes (Given)
0
Likes (Received)
10

how to gash it and hob it
Hi,

To do it right you need a hob. Store bought hobs cost a lot. There are a lot of pitches out there, worm sizes, etc. no job shop has it all so here is our workaround for 1 shot gear fabrication in bronze.

You will need a lathe, a bridgeport or equivalent, a dividing head with tailstock, a boring bar that holds a tool bit that will fit the bridgeport, a torch or oven.

To make the hob get a steel you can harden I always go cheap on this cause its a one shot tool. I use 1144 stressproof, easy to cut, gets hard as glass if water quenched from red heat.

The hob will be a shank hob, the shank end fits your bridgeport collet, the worm end will do the work. Turn the worm od .314 x the diametral pitch larger than the existing worm and a inch longer in length than the old worm. Its probably 29 degree single start so grind you up an acme style thread bit to fit the old worm good and chase the threaded section maintaining the root diameter as a tooth thickness control unless you have a set of gear tooth verniers to measure the pitch thickness.

The hob should now look like the old worm on a stick so to speak. Now you have to flute it. put it in an indexer in the bridgeport and set the end mill side on the centerline and cut straight flutes on it, I usually put 3-4 on a 3/4 od worm thread. Remove any burrs but remember these edges are your cutting teeth so NO chamfers just get the hangers off there.

If you used stressproof heat the worm section red and drop straight into a bucket of lukewarm water, NOT COLD WATER, obviously there is a risk here of splashing hot water, shattering steel, etc, etc. Be Cautious if its your first time heat treating. You can always go the high dollar road and use A2 or D2 and air quench if the water quench shakes you up. We just want it hard, how you get there is up to you.

Now for the worm wheel, turn up the blank with provisions for putting it between centers on a pressed in mandrel or built in shank depending on how its made. Get it in the bridgeport, with the indexer set up for the number of teeth. At this stage you could hold the mandrel in a chuck or collet or on centers with a clamped dog.

Take your lathe tool bit from chasing the worm and put it in a boring bar in the mill spindle. Try to get the tip of the tool so it would bore a hole the same size as the hob od, if thats too small of a circle go as small as you can. Tilt the bridgeport head to the helix angle of the worm and gash the teeth as other posts show, 1 pass around, gash depth should be about 1.7-1.9 x diametral pitch to leave stock for the hob.

Now take out the boring bar and put in the shank hob, set your spindle rpm relatively slow 100-200 rpm, put the mill head back vertical. Get the part between centers, no dog, grease on centers, it must turn free but not sloppy. Bring the hob into mesh with the gashed blank with the spindle OFF until there is about .015 slop or clearance. Make sure you start the spindle in the proper direction.

Feed it in slow by hand, there will be a lot going on with the cutter turning and the worm turning and your probably nervous cause its scary looking. The total depth of a standard tooth is like a spur gear 2.157 x dp. Don't be afraid to stop the mill and put the real worm in mesh and measure the center distance, take it out and try it in the saw if you have to, you can always put it back in and shave off some more.

I cut bronze dry or with water soluble coolant if its a big one with more heat. Stress proof steel cutters don't like heat and they are very brittle. Once you learn how to do this a bronze worm gear under 8" od and 1" thick becomes about a 10 hr project if you tinker around with it or about 4 hours if you are in money making mode. I have done and seen done 30-40 of these in my life using this method cause its cheap, effective, and easy. After all laziness is the true mother of invention.

Rock

Now that WOULD be an awesome @doubleboost Nite cap.

 

[Spark plug]

Is the gearbox part of the mincer or is it seperate?

If it is seperate it might be easier to find a replacement gear motor that will fit/can be grafted on.

 

[Maker]

I saved this from another site, not tried it my self yet I need to cut a worm wheel for a saw

rockcampbell

Aluminum

Join Date
Dec 2002
Location
kentucky
Posts
106
Post Thanks / Like
Likes (Given)
0
Likes (Received)
10

how to gash it and hob it
Hi,

To do it right you need a hob. Store bought hobs cost a lot. There are a lot of pitches out there, worm sizes, etc. no job shop has it all so here is our workaround for 1 shot gear fabrication in bronze.

You will need a lathe, a bridgeport or equivalent, a dividing head with tailstock, a boring bar that holds a tool bit that will fit the bridgeport, a torch or oven.

To make the hob get a steel you can harden I always go cheap on this cause its a one shot tool. I use 1144 stressproof, easy to cut, gets hard as glass if water quenched from red heat.

The hob will be a shank hob, the shank end fits your bridgeport collet, the worm end will do the work. Turn the worm od .314 x the diametral pitch larger than the existing worm and a inch longer in length than the old worm. Its probably 29 degree single start so grind you up an acme style thread bit to fit the old worm good and chase the threaded section maintaining the root diameter as a tooth thickness control unless you have a set of gear tooth verniers to measure the pitch thickness.

The hob should now look like the old worm on a stick so to speak. Now you have to flute it. put it in an indexer in the bridgeport and set the end mill side on the centerline and cut straight flutes on it, I usually put 3-4 on a 3/4 od worm thread. Remove any burrs but remember these edges are your cutting teeth so NO chamfers just get the hangers off there.

If you used stressproof heat the worm section red and drop straight into a bucket of lukewarm water, NOT COLD WATER, obviously there is a risk here of splashing hot water, shattering steel, etc, etc. Be Cautious if its your first time heat treating. You can always go the high dollar road and use A2 or D2 and air quench if the water quench shakes you up. We just want it hard, how you get there is up to you.

Now for the worm wheel, turn up the blank with provisions for putting it between centers on a pressed in mandrel or built in shank depending on how its made. Get it in the bridgeport, with the indexer set up for the number of teeth. At this stage you could hold the mandrel in a chuck or collet or on centers with a clamped dog.

Take your lathe tool bit from chasing the worm and put it in a boring bar in the mill spindle. Try to get the tip of the tool so it would bore a hole the same size as the hob od, if thats too small of a circle go as small as you can. Tilt the bridgeport head to the helix angle of the worm and gash the teeth as other posts show, 1 pass around, gash depth should be about 1.7-1.9 x diametral pitch to leave stock for the hob.

Now take out the boring bar and put in the shank hob, set your spindle rpm relatively slow 100-200 rpm, put the mill head back vertical. Get the part between centers, no dog, grease on centers, it must turn free but not sloppy. Bring the hob into mesh with the gashed blank with the spindle OFF until there is about .015 slop or clearance. Make sure you start the spindle in the proper direction.

Feed it in slow by hand, there will be a lot going on with the cutter turning and the worm turning and your probably nervous cause its scary looking. The total depth of a standard tooth is like a spur gear 2.157 x dp. Don't be afraid to stop the mill and put the real worm in mesh and measure the center distance, take it out and try it in the saw if you have to, you can always put it back in and shave off some more.

I cut bronze dry or with water soluble coolant if its a big one with more heat. Stress proof steel cutters don't like heat and they are very brittle. Once you learn how to do this a bronze worm gear under 8" od and 1" thick becomes about a 10 hr project if you tinker around with it or about 4 hours if you are in money making mode. I have done and seen done 30-40 of these in my life using this method cause its cheap, effective, and easy. After all laziness is the true mother of invention.

Rock

I got a bit confused reading that so I had a look on youtube;

Doesn't look to hard. Also, I'm very impressed with the strength of Loctite 638.

 

[WorkshopChris]

There is :-
machining then

gear cutting then
hobbing gears ( more commonly known as voodoo or witchcraft depending what part of the country you come from)

 

[normspanners]

Last gear I had remanufactured was by Bill at;

Billcar Precision Engineering Limited
Unit 1A, Battlefield Enterprise Park Shrewbury
01743 450044

 

[ukracer]

Last gear I had remanufactured was by Bill at;

Billcar Precision Engineering Limited
1 review · Precision Engineer

Unit 1A, Battlefield Enterprise Park shrewbury
01743 450044

is the the Nissan specialists?

 

[normspanners]

As well as engine work He does all kinds of engineering he has a vast range of machines and has one of the biggest lathes in uk apparently,

I have done some work in his place on a couple of his machines when we were desperate for a part and needed machining doing and he had no one spare.
they are very helpful.

 

[armalites]

Try these guys
http://www.hewitt-topham.co.uk/

 

[Woody.v8]

I've used these in the past, very good service, http://leekgears.co.uk