Non breaking... gear for 7x10 mini-lathe?

[jinu117]

Well, it happened. After 3 months of using 4" 3 jaw chuck on 1.5" copper bar stock (yes... not the easiest thing to do with 7x10 as I have found), the thing just stalled and wouldn't turn. I disassembled whole thing (including headstock) and found out the spindle gear inside is cracked in half.... plastic gear). Is there stronger replacement gear? I've seen one set of spindle gear in aluminum which cost... $70-80 (bit high) made out of aluminum but I am not sure if it is THE solution or if there is something better out there. (no I really don't have use for bigger lathe as I will be soon getting 4 axis cnc mill and will be using that more often other than for "parting" cut or some quick things I am going to full around).
Thanks for any insight you can give me

[USMCPOP]

Maybe here?

http://www.littlemachineshop.com/pro...First=G&Last=G

[gmac]

the next strongest would probably be zinc - and the part can be made from starting with the one you have. glue the broken plastic one together so it makes the correct form, use it for the master for the silicone mold for the zinc one, then use the mold to cast the zinc one. then you can sell the next few to us who havent broken ours yet. not as easy as it sounds but makes a decent gear - there are bulletin boards on casting metals into silicone molds that make the process fairly easy and one of the nice folks there might just do the whole thing for you for a few simoleons. similar/ same procedure in sand or plaster casting for other materials including heat-cured ceramics or maybe polymer clay. might use heat-curing , UV, or otherwise, maybe try glass-filled epoxy or other compounds also. take your pick -there are lots of ways to get there. you could cast another one in just same plastic but put a reinforcing band of coiled steel wire in it to prevent the cracking from expansion forces, as long as the gear teeth were wearing OK then your problem could be solved.

[carlnpa]

I consider the plastic gear to be the equivalent of a fuse. They are cheap and easily replaced. Pick up a handfull and replace as needed.

[S_J_H]

The plastic spindle gear is no piece of cake to change! That gear is inside the head between the 2 spindle bearings. The spindle needs to be removed to change the gear. I have broken it on my 7x10 also. The mini mill also uses the same plastic gear on the spindle for the 2 speed drive but that is not the gear most people break on the mill.
Micro Mark uses metal spindle gears. Maybe just the gear can be purchased from them.
Steve

[JDsto]

micro mark has the metal one for in a replacement kit for 64.00. I think I'll order it cause I added a 4 inch chuck to my 7x12 and now when I run faster speeds it will all of the sudden make a loud humming sound and vibrate , I assume that its this plastic gear that has a broken tooth or two. I turn the lathe off and restart and then it will be okay for a few minutes until it does it again. does that sound familiar for those that have had to replace the gear?

[pastera]

With the 4" chuck the adapter normally is set up for both the 3 and 4 bolt spindles. This makes the adapter off balance and it will vibrate quite a lot over ~600RPM. Take a look at the adapter plate and turn plugs from steel for the unused holes.
My 4" 4-jaw runs smooth at top speed in high gear with the adapter plate modified in this way.

Aaron

[JDsto]

Thanks I'll take a look at the adapter plate. All I know is I'll do what ever I have to, There is no going back to that 3" chuck.

[philbur]

You could make one using your new milling machine

Regards
Phil

Well, it happened. After 3 months of using 4" 3 jaw chuck on 1.5" copper bar stock (yes... not the easiest thing to do with 7x10 as I have found), the thing just stalled and wouldn't turn. I disassembled whole thing (including headstock) and found out the spindle gear inside is cracked in half.... plastic gear). Is there stronger replacement gear? I've seen one set of spindle gear in aluminum which cost... $70-80 (bit high) made out of aluminum but I am not sure if it is THE solution or if there is something better out there. (no I really don't have use for bigger lathe as I will be soon getting 4 axis cnc mill and will be using that more often other than for "parting" cut or some quick things I am going to full around).
Thanks for any insight you can give me

[keithw]

These people have lots of spares/accessories for the minilathes/minimills, including a metal replacement for the internal headstock bearings (just under 10 pounds English when I looked - they also do taper bearings for the headstocks (same bearings in lathe and mill - made a 'big' difference to my machines)

http://www.arceurotrade.co.uk/