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D-man
20-10-2014, 08:24 AM
Hi guys, I've purchased 2 x cncrouterparts pro drives with the plan to swap to pinions in the pulleys to mod1, now this is proving to be a right pain to get them swapped... does anyone know where I can get the imperial rack from in the uk? It's 20 degree with 20mm pitch

charlieuk
20-10-2014, 09:48 AM
i did the exact same thing only a few weeks ago with a great result! finding imperial rack is imposable without getting it made for you and that was going to cost a packet.

All you have to do is separate the steel pinion from the large pulley, i tried everything from freezing to trying to remove the barring with no luck so ended up using a very sharp but old chisel and taped it in between the two to get enough of a gap to separate them which worked very easily after days of trying other ways!

I then noticed that the hole was the exact size of the boss of a mod1 pinion so i got a couple of sizes from cnc4u and tock them to a machine shop and hand him bore out the centre to match and then i milled the small key way into it myself. I think i ened up using the 25 tooth pinion as i wanted the smallest posable.

the second issue though is now you will need a shorter axel and they are hardened so you can machine it so what we ended up doing was making a small s/s steel spacer to go on the axel to push the pulley and pinion back out so a very simple fix using a pice of 1/2" tube and that was it job done and works a treat and all working on my machine.

magicniner
20-10-2014, 09:58 AM
HPC Gears supply racks in metric and Imperial - http://www.hpcgears.com/n/products/11.racks/racks.php
They supply anti-backlash spur gears too!

D-man
20-10-2014, 10:22 AM
Thanks Charlie, i will look into doing that, however im using the 35 tooth pulley. could you explain exactly how you got it out as i dont quite understand about the taped?

charlieuk
20-10-2014, 10:29 AM
Thanks Charlie, i will look into doing that, however im using the 35 tooth pulley. could you explain exactly how you got it out as i dont quite understand about the taped?

sorry probably my spelling the larger pinion shouldn't be a problem. I tock a hammer and chisel and carefully put it at the back of the teeth of the pinion and gave it a light tap with the hammer and moved my way around the pinion a bit at a time, the teethe have a slight chamfer on the back so it actually makes it come out very easy.

D-man
20-10-2014, 10:37 AM
Oh mine are completely flush with the pulley. I will give it a "bash" pun intended haha cheers

charlieuk
20-10-2014, 10:58 AM
im only talking .5 of a mm chaffer but its enough to help get a sharp chisel in to start it of, once i had a small gap i could get in with a puller (in my case a few larger levers) to ease it up evenly. If you have a lathe all all the bits its probably a hours work thats all.

charlieuk
20-10-2014, 11:07 AM
im only talking .5 of a mm chaffer but its enough to help get a sharp chisel in to start it of, once i had a small gap i could get in with a puller (in my case a few larger levers) to ease it up evenly. If you have a lathe all all the bits its probably a hours work thats all.

This shows the spacer on the shaft behind the pulley and also the bracket I made to take the hole thing crude but functional

D-man
20-10-2014, 11:26 AM
Your a gent! I shall let you know when I cock it up and will be at your door with a new set for you to do for me haha

Nice piece of kit ain't they.

charlieuk
20-10-2014, 11:42 AM
as i say i got some one else to do the hard bit of boring out the new pinion, i have a lathe but not the correct tooling so thought just take it a get it done as i was loosing patience with myself and it. I was concerned about hanging a big nema34 off it but they are supper solid its just a shame they dont do them in a metric option. If i do a 8x4 build myself i would get two more defiantly.