# Lms 3990 Mini Mill... Upgrades



## intrepid

I have decided to buy the LMS 3990 mini mill.  I plan to add the table feed and column spacer for added work height.  Those who have this machine or are also planning to get it, Are there any other upgrades you would do to the machine?  Not talking about tooling accessories, rather the machine itself.


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## intrepid

Wow, maybe not many have or use this mill.  I thought it was popular,  maybe not.


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## higgite

There are some LMS owners here. I’m one but I don’t have a 3990 mill that you’re asking about. I don’t know why there isn’t an LMS subforum among the multitude of other manufacturer/vendor subforums. You might try posting your question in one or more of these.

Asian Mills & Lathes
Charter Oak Automation Machines (Charter Oak CNC Mills & Little Machine Shop machines)
Various Other Brands of Machinery
General Discussions
A Beginner’s Forum
Questions & Answers

Tom


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## Charles Spencer

It's probably also worthwhile to check out other versions of the X2 mini mill as well.  Hoss Machine has a lot of info:

http://www.hossmachine.info/


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## Greebles

I have a LMS 3990 and PM-727M. I find having the LMS mill very handy for smaller work.


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## intrepid

Greebles said:


> I have a LMS 3990 and PM-727M. I find having the LMS mill very handy for smaller work.


Hi GR,
Thanks for responding.  I've downsized very much and will only be doing small projects and some hobby model things now.  However, since this will be my only mill I would like to make it as universal as possible.  Have you done any modifications to your mill?  I plan to add a column spacer, spindle lock, and table feed.  Maybe later a DRO.  Since I will be reshipping it overseas to my retirement home once I receive it, I would like to purchase whatever modify pieces I need all at once.  I have plenty of R8 tooling so that is not a problem.  Do you plan any mods or see any needs for the machine?


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## Greebles

First thing I did was add iGaging Absolute DRO for all axis. Second was an air spring to help lift the head and eliminate head drop.

I am currently considering / planning converting it to CNC.


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## Ken from ontario

I was just browsing through the sub forums and found this thread, I recently bought a Canadian version of the LMS 3960, (Busy Bee  Craftex CX-612) , I love milling with this little  machine but it didn't take me long to figure out what immediate upgrades it needs ,first and foremost is installing XYZ digital readouts, there are a couple of DRO kits available  but I'm not sure if I must first replace the torsion spring to an air strut in order to free up some needed space for the Z DRO sensor (Z axis) or if it can be placed on the right side of the column?
Anyhow, I think the biggest improvement we can make for this mini mill is to install  a DRO kit and be done with calculating  in 1/16"s. as far as installing a gas strut, it seems to be an easy conversion ,MLS sells the whole kit for $50,I'm wondering if I should buy the kit  or just buy the necessary parts  and machine the brackets myself. 

Best of luck to you Intrepid, hope you manage to do all the upgrades you need  but I think the two I mentioned (DRO/ spring conversion) will make a huge difference in the performance of any mini mill.


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## Zoltan

You should immediately add a DRO since it makes the machine soooooooooooooooo much nicer to use. Check out the Android tablet based TouchDRO system. It's inexpensive to make, very full featured, and wonderful to us. Having a DRO is indescribably better than counting handwheel turns and dealing with backlash.

My other mods:
http://benchtopmachineshop.blogspot.com/

You can also build a nice power table feed for under $50. I also highly recommend modifying the gibs as it helps rigidity and makes it smoother. Also add a spindle light since it's pretty cheap and easy. But seriously, get a DRO.


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## intrepid

Greebles said:


> First thing I did was add iGaging Absolute DRO for all axis. Second was an air spring to help lift the head and eliminate head drop.
> 
> I am currently considering / planning converting it to CNC.



I was going to do a DRO later but maybe I should consider it sooner.
The LMS 3990 states it has a gas strut.  Is that different from the air spring?  The picture of the air spring conversion looks like a gas strut.

Danny
Laguna, Philippines


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## intrepid

Zoltan said:


> You should immediately add a DRO since it makes the machine soooooooooooooooo much nicer to use. Check out the Android tablet based TouchDRO system. It's inexpensive to make, very full featured, and wonderful to us. Having a DRO is indescribably better than counting handwheel turns and dealing with backlash.
> 
> My other mods:
> http://benchtopmachineshop.blogspot.com/
> 
> You can also build a nice power table feed for under $50. I also highly recommend modifying the gibs as it helps rigidity and makes it smoother. Also add a spindle light since it's pretty cheap and easy. But seriously, get a DRO.




Well, everyone suggests a DRO first.  I have been milling on a manual floor model mill for years without DRO.  But maybe I will consider it now.  Thanks very much for your thoughts and ideas.  I'll need to spend some time reading your link.  Looks very interesting.  Is the $50. powere feed and gibs modification in link?

danny
Laguna,  Philippines


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## Ken from ontario

*I*f I understand these modifications correctly,I don't think you could instal the dro sensor/bracket on Z column with the original torsion spring still in place, the gas spring should be installed first ,I copied and pasted the direction from Zoltan's link but I'm having a hard time understanding how he fitted the  oval shaped UHMW in the base ,there's no pictures of the installation of it,which is unfortunate.


_*I grabbed a piece of 1.5" UHMW tube left over from another project, cut it down to 5 inches long, and then squeezed it into an oval cross section using my bench vise and heat gun. I then drilled a 8mm hole through it 4.5" from the end. One end of the gas spring is bolted through using the hole, and it's then lowered down onto the column. The UHMW tube then site on the mill's base inside the column and spaces the gas spring correctly. This way there's one less hole in my column.*_
I have seen a few youtube videos of this seemingly easy  "gas strut/spring conversion" but none has a step by step direction on how to do it ,they all show the installation after it's done.


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## intrepid

Ken from ontario said:


> *I*f I understand these modifications correctly,I don't think you could instal the dro sensor/bracket on Z column with the original torsion spring still in place, the gas spring should be installed first



Thanks Ken.  That makes since what he says about the torsion spring.  However, LMS shows the new version 3990 mill comes with a* gas strut.*  Others here are mentioning an *air spring*.  I'm wondering if the gas and air spring are one and the same?

BTW, I was looking at the Igaging DRO and looks like I'll be ordering them also.

danny
Laguna, Philippines


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## Ken from ontario

Intrepid, the air spring and gas strut  is the same thing as far as I know ,even if there's a difference in mechanism,for this application  it is one and the same.
The MLS 3990 does come with a gas spring already installed  I have the 3960 with the older torsion spring but the only reason I am changing it is  to install the DRO,I found a local vendor who sells them (IGaging)for under $150 in Canada, it seems to be as accurate as the newer model EZ View DRO.
I'll order mine after I replace the gas spring.


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## intrepid

Ken from ontario said:


> Intrepid, the air spring and gas strut  is the same thing as far as I know ,even if there's a difference in mechanism,for this application  it is one and the same.
> The MLS 3990 does come with a gas spring already installed  I have the 3960 with the older torsion spring but the only reason I am changing it is  to install the DRO,I found a local vendor who sells them (IGaging)for under $150 in Canada, it seems to be as accurate as the newer model EZ View DRO.
> I'll order mine after I replace the gas spring.



That's what I was thinking Ken.  They are the same.  So that is one mod I will not have to do.   Seems like a good price for the IGaging DRO.  I found a vender on flebay selling a three piece set, 6", 12", and 24" for $129.99  and free shipping in the US.  $36.00+ for shipping to Canada.


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## MikeinFresno

I found that the air spring in my 3990 does make it quite smooth and easy to lower the head, but still a little harder going up since you are lifting the head. Im hoping it gets smoother as a I use it.
For mine I purhased the DROs from LMS while I was there picking up the machine. Still working on getting it all squared up and trammed. Cant wait to get to cutting.


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## Ken from ontario

MikeinFresno said:


> I found that the air spring in my 3990 does make it quite smooth and easy to lower the head, but still a little harder going up since you are lifting the head. Im hoping it gets smoother as a I use it.
> For mine I purhased the DROs from LMS while I was there picking up the machine. Still working on getting it all squared up and trammed. Cant wait to get to cutting.



I replaced the torsion spring  on my 3960 to LMS air spring  last week , the head on mine also is harder on the way up but as you mentioned it should get smoother with time and usage but overall, it's smoother than before and also a necessary upgrade (IMHO) to free up some space on the column for the Z axis DRO.

Today I spent a good 4-5 hours installing the X axis ,I already installed an Aluminum angle on the back of the bed , tomorrow I'll attach a bracket to the reader unit and  the X axis will be done.
The Y and Z axes should be easier to install, I hope.


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## MikeinFresno

Im down with a bad flu for 7 days now. Not enuf energy to get to it for a few more days I think. All this sitting just gives more time to think and read tho.


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## Ken from ontario

There's a nasty flu bug going around this year, so far my wife and I haven't got it yet,(knock on wood), hope you get better soon.


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## Zoltan

Ken from ontario said:


> *I*f I understand these modifications correctly,I don't think you could instal the dro sensor/bracket on Z column with the original torsion spring still in place, the gas spring should be installed first ,I copied and pasted the direction from Zoltan's link but I'm having a hard time understanding how he fitted the  oval shaped UHMW in the base ,there's no pictures of the installation of it,which is unfortunate.



I didn't really "fit" anything in the base. The UHMW was used to space the gas strut the correct distance from the base, the strut was then bolts to the UHMW, and then both were lowered down into the column.


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## Ken from ontario

Zoltan said:


> I didn't really "fit" anything in the base. The UHMW was used to space the gas strut the correct distance from the base, the strut was then bolts to the UHMW, and then both were lowered down into the column.


Thanks Zoltan for clarifying how you used the UHMW spacer ,I understand it now.
Following  the instruction that came with the LMS air spring kit, I just measured 14.1/2" from the top of the column and drilled a hole in the center of it.


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## Four Corners

I have the 3990 and am very impressed by it. Can't think why it doesn't have a reverse switch though. Check this out: http://macpod.net/misc/sx2_tachometer/sx2_tachometer_kit_v2.php. Now my mill has a reverse for less than $10. Power tapping is a real option now. The tach in that link looks great, and I might get it one day.


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## Ken from ontario

4 corners,That would be a good upgrade, I thought about buying the Busy Bee RPM display that is specifically made for  mini mills but the cost was too high($165 + tax), there is a  handheld version  for under $20.
If you can manage to do the upgrade you linked, yourself, it shouldn't cost that much.


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## Four Corners

That fellow seems to be asking USD 50 for the kit. The reverse switch was so rediculous simple!  I used it today to tap some 1/4 20 holes in a QCTP holder I made. 
I'm sure the kit that includes the tach is almost no work. Very tempting. As a novice machinist I've already smoked a couple of cheap chinesium end mills. My fault entirely, not the tools. I'm glad they weren't have decent cobalt end mills. I'm much more familiar with screaming router bits eating through maple. 4140 is not maple, apparently. If I had paid attention to the feeds and speeds charts, and had a way to know the speed, I might (possibly, who knows) have not ruined the end mills.


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## Charles Spencer

Four Corners said:


> had a way to know the speed, I might (possibly, who knows) have not ruined the end mills.



I use a non contact tachometer.  I also use it on my drill presses, lathes, etc.  Easily worth it for $10:

http://www.ebay.com/itm/Digital-Las...ach-Meter-Motor-Speed-Gauge-USA-/140666635376


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## Al-Hala

Four Corners said:


> ... If I had paid attention to the feeds and speeds charts, and had a way to know the speed, I might (possibly, who knows) have not ruined the end mills.




Four Corners, you are hardly alone in doing that; I've about $100 of "wall of shame" myself before I got the hang of it. You might want to look at either CNCCookbooks' G-Wizard, or High Speed Machining Advisor for your feed and speed needs. both are mature (and continually upgraded) programs that are used by numerous hobbyist class users.


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