# Mini-mill crash and burn



## Brian H (Apr 1, 2019)

So.....
Last weekend I got a bit aggressive (read-lazy) and skipped a couple sizes while trying to drill a 27/64" hole in some 1/4" steel and busted one of the drive gears (lovely chinesium plastic) inside my mill. 
After seeing a few less than favorable you tube reviews on the fit/finish of the pieces, I hummed and hawed for about and hour on purchasing the belt drive conversion and then bit the bullet and ordered it.
Surprisingly, it showed up in 6 days (instead of the 2-3 week shipping time they tell you) and I just got it installed. I have noting but great things to say about what a difference it made, and the quality is very good. I cannot get over how quiet and smoothly it runs.
The big question is what project shall I do first....


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## YYCHM (Apr 1, 2019)

I take it you got the LMS upgrade kit?  What did it end up costing landed?


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## Everett (Apr 2, 2019)

My dad has a mini-mill and he wound up putting the belt conversion into his as well after tearing up the gears.  He says it was a serious upgrade to his too.


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## YYCHM (Apr 2, 2019)

Everett said:


> My dad has a mini-mill and he wound up putting the belt conversion into his as well after tearing up the gears.  He says it was a serious upgrade to his too.



Serious as in "difficult to do" or serious as in a "significant improvement"?


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## Everett (Apr 2, 2019)

He said it was easy enough to install, but that it was a definite improvement over the gears that came in it originally. He bought all his stuff when he was working in the US a few years before he retired, but not sure if it was LMS or elsewhere.


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## Brian H (Apr 2, 2019)

YYCHobbyMachinist said:


> I take it you got the LMS upgrade kit?  What did it end up costing landed?


After postage, exchange and taxes about $230


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## YYCHM (Apr 13, 2019)

Mine bit the dust today.






Attempting to drill a 1/2" hole to 11/16".

Kind of puts my current project on hold :-(

Will have to give the belt upgrade serious consideration now.

Hmmm.  The mill was purchased 8/9/2018.  Still under warrantee.  I wonder if this is covered????


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## Janger (Apr 13, 2019)

If you can find the stl file I’ll print you a new one out of ABS. Be interesting to see if it lasts or not. I think there is a program out there that will generate the model ....


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## Brian H (Apr 13, 2019)

That looks like the one at the top of the mill. I have my old one if you want it. (Send me the number of teeth etc and Ill check that its the same). The ones that busted on mine were the internal ones. From what I've read the top one is supposed to break before the internal ones do since its the easiest to change.


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## YYCHM (Apr 13, 2019)

Brian H said:


> That looks like the one at the top of the mill. I have my old one if you want it. (Send me the number of teeth etc and Ill check that its the same). The ones that busted on mine were the internal ones. From what I've read the top one is supposed to break before the internal ones do since its the easiest to change.



PM sent.


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## YYCHM (Apr 13, 2019)

Janger said:


> If you can find the stl file I’ll print you a new one out of ABS. Be interesting to see if it lasts or not. I think there is a program out there that will generate the model ....



STL file?

This is the gear that cratered on me.  Is there a program that will gen a STL file from this description?

https://littlemachineshop.com/products/product_view.php?ProductID=1209


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## Tom O (Apr 14, 2019)

I see that you can upgrade to a metal one for $18 and change.


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## Brian H (Apr 14, 2019)

I feel you would need to upgrade all 3 gears if you went in that direction. There's no point in relocating the "weak link"


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## YYCHM (Apr 14, 2019)

Brian H said:


> I feel you would need to upgrade all 3 gears if you went in that direction. There's no point in relocating the "weak link"



My thoughts as well.  Might as well just remove the plastic gears from the equation all together.  Sounds like the belt drive runs smoother to.


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## YYCHM (Apr 14, 2019)

This guy is pretty entertaining....


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## Tom O (Apr 15, 2019)

Have you tried looking on thingiverse they have just about everything in 3D printed gears.
I just entered mini mill and this popped up.
https://www.thingiverse.com/thing:947572
Check out the comments though.


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## Brian H (Apr 15, 2019)

Yes, I like when he splits his piece of oak in two. I guess they have different oak than we do. I'd have to smack the stuff I have pretty good to split it. Interesting video tho


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## YYCHM (Apr 15, 2019)

Janger said:


> If you can find the stl file I’ll print you a new one out of ABS. Be interesting to see if it lasts or not. I think there is a program out there that will generate the model ....



Tom O found the STL file.   Thanks Tom O!

https://www.thingiverse.com/thing:947572

Can you print in Nylon?  Apparently ABS won't last more than an hour.  See thinginverse comments.


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## Bofobo (Apr 15, 2019)

Once you upgrade to metal gears you will find the true weak link is in fact the motor as it stalls even trying to drill your half-inch holes a belt drive will still stall the system but is supposed to run quieter though I never bought the metal gears to try I went straight to belt drive currently the 2 hp motor  Will slip on the belt drive if I try to take too big of a cut and I may go to metal gears myself one day


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## Janger (Apr 16, 2019)

Oh cool guys. I don’t have any nylon. I can print it though. Anybody got nylon and can help out yychobbymachinist? @Jwest7788 @Johnwa ?

YYC if you want to buy some I’ll print your part. There’s a store in the SE near princess that sells it. Spool3d it’s called. 1.75mm diameter.


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## YYCHM (Apr 16, 2019)

Janger said:


> Oh cool guys. I don’t have any nylon. I can print it though. Anybody got nylon and can help out yychobbymachinist? @Jwest7788 @Johnwa ?
> 
> YYC if you want to buy some I’ll print your part. There’s a store in the SE near princess that sells it. Spool3d it’s called. 1.75mm diameter.



Brian H has mailed to me his now redundant gear.  Thanks Brian H!

BB has back ordered me two (one was covered by warrantee) but I won't see those until mid May.

This should keep me going until LMS has the belt drive/air spring upgrade kits back in stock.

Thanks guys.

Bofobo:  Did you pull all the gears out of your machine?  BB told me the internal gears are metal.


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## Tom O (Apr 16, 2019)

Janger said:


> Oh cool guys. I don’t have any nylon. I can print it though. Anybody got nylon and can help out yychobbymachinist? @Jwest7788 @Johnwa ?
> 
> YYC if you want to buy some I’ll print your part. There’s a store in the SE near princess that sells it. Spool3d it’s called. 1.75mm diameter.



I don’t have nylon either I dusted off my printer yesterday as my granddaughter wanted a figurine of Baby Groot off of Guardians of the Universe so back to the learning curve. I will have to look for a different version slicer though that has 2 extruders capability.
It printed ok but at the 3 - 3 1/2 inch mark it breaks loose from the platform! But I have a idea  that could save a lot of prints like this “ Stay Tuned “.


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## Janger (Apr 16, 2019)

I had the same problem printing that groot model! I read up that acetone is useful to restore the gripping strength of the metal printing plate. Try that if you have a metal plate. After I could print groot.


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## Tom O (Apr 17, 2019)

Well I haven’t used my printer for years really so it started off bad lol the filliment would clog  after about a hour so I switched to a new roll, then using the sd card I unplugged the cable from the laptop killing the print WTF? This happened again as I decided to charge my old laptop while waiting for the print that I was about a hour and a half into it turns out the power cable wasn’t plugged all the way in!  After that the body printed fine the head ( a 3+ hour job ) was down to the last 45 min or so and broke loose! So on to print 2 it’s going great and has just a 1/2 x1/2 left to go and breaks loose again so close!




So now I’m thinking Ch Ch Chia Pet






I haven’t started the third print yet to think about it and have decided to make a tool for this type of build that has a small base to height ratio here’s my idea






The two pegs on the bottom go under the build plate the pivot is say 1/4” rod that the ends slide on to and the tension screw to clamp down on the rafting.
Hopefully with this even if it breaks away it should be able to finish the print just make sure you put something under the tension screw to protect your build plate.


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## CalgaryPT (Apr 17, 2019)

Bofobo said:


> Once you upgrade to metal gears you will find the true weak link is in fact the motor as it stalls even trying to drill your half-inch holes a belt drive will still stall the system but is supposed to run quieter though I never bought the metal gears to try I went straight to belt drive currently the 2 hp motor  Will slip on the belt drive if I try to take too big of a cut and I may go to metal gears myself one day


Isn't there a safety factor here in having a sacrificial gear on these little machines?


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## Tom O (Apr 17, 2019)

I would think that you can tell just by the sound of the machine if you are pushing too hard but if you stay with the plastic gears you may have to wait for another gear to come in and might have to limit extended cutting time because of heat on the gears.


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## Janger (Apr 18, 2019)

Tom O said:


> Hopefully with this even if it breaks away it should be able to finish the print just make sure you put something under the tension screw to protect your build plate.



Interesting idea. Get printing it? Would you want two? The prusa bed moves in the y axis but I think this could work in my printer too. Model it up Tom!


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## Tom O (Apr 18, 2019)

I should get on it today it won’t be hard to model up, I was thinking though why have 2 pins per side when one will do it’s just a anchor.


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## Tom O (Apr 18, 2019)

And now to the original post when I first got ny Craftex mill it was cutting good and I wasn’t pushing it to hard my son took over and I could hear the difference in the cut as he was unknowingly pulling the 3/8 cutter out of the R8 holder, this was followed by the machine stopping and taking a closer look at the electrical boards I found the donut choke thing had melted the solder detaching it and was sitting on the wires below it.


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## Bofobo (Apr 18, 2019)

CalgaryPT said:


> Isn't there a safety factor here in having a sacrificial gear on these little machines?


Well i had very little trouble causing the machine to stall by hand (grab running spindle and stall motor) so i dont think the weak gears are the fail safe, the motor “stalls” to protect it or some junk.


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## Brian H (Apr 19, 2019)

YYCHobbyMachinist said:


> Brian H has mailed to me his now redundant gear.  Thanks Brian H!
> 
> BB has back ordered me two (one was covered by warrantee) but I won't see those until mid May.
> 
> ...



I think I'd be a bit skeptical about having metal gears inside. I'm not aware of any that came that way from the factory.


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## YYCHM (Apr 19, 2019)

Brian H said:


> I think I'd be a bit skeptical about having metal gears inside. I'm not aware of any that came that way from the factory.



BB was full of BS when they told me the internal gears are metal.

Every one of LMS's direct replacement gears are plastic.  LMS lists metal replacements for all the gears but I think I'll go the belt drive route and be done with them.


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## Jwest7788 (Apr 24, 2019)

I haven't yet got into nylon, sorry!


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