# Help With Central Machine 7x10 Lathe Post Upgrades



## mzvarner (Apr 29, 2016)

This is a continuation of a similar thread in the "harbor freight..." machine section. I am posting these questions here because I hope to get more traffic thus more answers.

I am new to home machining and bought this used 7x10 on a whim. I recently upgraded the bearings to tapered roller bearings, ordered the larger spindle from London, and had to add/ replace various gears (replaced to metal from LMS). 

So all the work is done, but i am having issues now. The machine bogs down more easily. I am wondering if this is due to the preload I have set? I was not able to find many resources on how to correctly set preload. Here is how I have it now: when you remove the 2 spindle nuts there is a fair amount of lateral play that i believe is just inherent in this design of bearing since there are a few parts that must mesh together. All of this play goes away when the nuts are installed, but then there is little "free wheeling". (If i disengage the gears and spin the chuck by hand I get 2-3 rotations then friction stops it.) Also I think I need to trim down the plastic spacer because the spindle gear will not full mesh with the pinions (off about .075). This was one of the reasons I have so much preload, I was trying to force the gear into alignment.  

The other issue is that I cannot disengage the lead screw unless I remove one of the pinions. It seems there is too much play in the mechanism that adjusts this. If I support the handle in the neutral position there is room, but as soon as i remove the support the gears try to mesh. Is there a simple way to fix this?


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## Sitting on Blocks Racing (Apr 29, 2016)

I have a similar problem on my Grixxly...I swapped a gear from LMS that I broke and now there is no neutral.   I normally have it powered so hasn't been an issue.   Sounds like the bearing preload is correct.    Since it's used, the motor could just be tired.


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## mzvarner (Apr 29, 2016)

I had thought about that but the machine was working fine. I only took on all the upgrades because I broke some gear teeth in the headstock and decided since I was going to have it all apart I may as well go all in. Not sure what I would have done to the motor or control panel while it was down.


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## mzvarner (Apr 29, 2016)

So maybe I figured out my own solution.

I tried a number of things. First I played with preload, but this did not seem to make much of a difference so it cant be the problem (yet). Next I looked at my tools. The index-able carbide is just that and seems fairly sharp. Then I have the brazed ones that were all used and came with the machine and are not as sharp. Then I have HSS blanks that I have not yet ground (so they are dull ) None of this made a difference. 

Then I decided to call LMS for some advice. They showed me how to trouble shoot the electronics because they thought that it sounded like that was the problem. I went through their test procedures, but nothing was out of wack. I did take the air compressor to the main control and the motor. I also used a rat tail file to cut new contact surfaces in the brushes (?) of the motor. I then placed everything back together.

This is when IT hit me... Before the upgrades I has only able to use the standard 3" 3 jaw. Now, I am using the 4" 4 jaw, and turning larger diameter test pieces (2 " 6061). Previously I was getting 0.02-0.03" depth of cut. Well I was forgetting to adjust my "feeds and speeds" for the larger stock. Once I started to run the machine slower and take .01 cuts and smaller I was getting better finishes.Problem solved!!...for now.

Now the only issue is that after running for "a while" (sorry, but I dont know the exact time frame) the head stock does smell hot. I am using white lithium grease for the head stock gears... does this matter?


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## Charles Spencer (Apr 29, 2016)

How often we check everything else we can think of when the solution is right before our eyes.


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## Bill Gruby (Apr 30, 2016)

I just saw this thread, sorry I'm late. The grease is OK to use but check it often. Your solution is correct in that the feeds and speeds are slightly different. Also you have more mass translate that weight to turn so speeds will need to be higher or you will get the bog down you spoke of. So far you are OK, just watch it for a bit. It will normalize and you will have no more problems like those.

 "Billy G"


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## royesses (Apr 30, 2016)

If you search ebay you will find a reduction belt and pulley set available for the mini lathe. It reduces rpm's but gives about 30% more torque. I've been running mine for a year now and am very happy with it. Here's the link I got it from:

http://www.ebay.com/itm/321948766897
(Go to the bottom of the page and see the new part listing . I am not associated with the vendor in any way. Just a purchaser.)
I think it was about $40.00 at the time. I bought 2 just to have a spare in case one gets damaged.

You should cut the spindle spacer to get your gears to mesh and adjust the spanners for zero free play plus a small amount more preload, like about 1/16 th turn of the spanner nut.

I am running the complete LMS metal gears on my mini lathe. I don't have any problem disengaging the lead screw. You may need to align the handle mount and pinions or re- drill the indent for neutral. All the parts of the gear train are rather loosely fit and allow for movement. When you disassemble the gear train you need to re align everything for best operation. It is all hand fit at the Sieg factory.

Hope this helps.
Roy


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## mzvarner (May 1, 2016)

Thanks for the advice. Much appreciated. I like the idea of the torque gearing I'll have too look around some cause the eBay link is no longer active.


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## royesses (May 2, 2016)

here is one listing on ebay:
http://www.ebay.com/itm/Asian-Mini-Lathe-7-x-10-12-14-Pulley-Belt-Reduction-Power-UpGrade/322084121906?_trksid=p2047675.c100011.m1850&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=36499&meid=a6845c3c421d42da8dc68e4885d70266&pid=100011&rk=5&rkt=8&sd=361519915501

There are many listings on ebay for the belt/pulley kits.

http://www.ebay.com/itm/Mini-Lathe-...008279?hash=item4afd1b5ad7:g:V7UAAOSwL7VWr~Fn

http://www.ebay.com/itm/Asian-Mini-...a9529cf&pid=100005&rk=5&rkt=6&sd=322074008279


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## mzvarner (May 2, 2016)

Wow not sure how I missed all of those. My googlefu is weak. Thanks again guys. Time to go turn the new spindle spacer!


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