# LMS 3960 or G0704 mill for a small lab?



## TIGL (Mar 19, 2014)

Hey all. I just joined the forum because I'm about to dive headfirst  into a project that's waaaaay more involved than than anything I've ever  tried before and I know I'll have questions. I'm pretty mechanically inclined (even though I'm trained  as a chemist) and my boss knows this so he goes and asks me to build  whats basically a bench mounted robot with stepper controlled leadscrews  and pneumatics (all automated). Anyway, I have a solid design mostly  worked out and soon it will be time to build it. Only thing is that we  don't have an in-house machine shop so we need to get at least a mill on  top of the raw materials. I'm putting together a requisition to order a  mill and for a while I'd been dead set on getting the solid column  Little machine shop mill with the tooling package but the more I thought  about it, the more I think it might be slightly undersized for what to  do. I was looking around for similarly priced machines that I could put  on the req as comparison quotes and stumbled on the G0704. Its about the  same cost shipped and has no tooling but a larger table

Enough  background, here's what I need to do: The core of this machine will be  an 18"x18"x1/2" aluminum base-plate to which everything will be  attached. In addition to the  1/4"-20 holes around the edge, I need to  mill four 5/8" slots in a cruciform pattern around the center.


​This certainly seems like it would be pushing the little machine  pretty hard but i think it should be doable. The center of the ends of  the slots are 5" from the edge and according to LMS, the throat on the  3960 is 6.5". I'd probably need to drill some extra 7/16" holes so that I  can use the clamping kit to bolt the plate to the table but it should  be possible, at least dimensionally, to make the part. The maintenance department has a  pretty beefy drill press so the  peripheral holes and any clamping holes should be able to be made  relatively easily on that. My main problem is the slots. According to Wolfram Alpha, the base will  weigh just under 16 pounds which I imagine is a good bit less than the  vice that will be mounted on the table most of the time. My main concern  is the torque since about half of the plate will be cantilevered off  the edge of the table which might put some unpleasant twisting stress on  the gibs and ways.

Unless I get a strongly negative  response from the HM brain trust, I'm still leaning towards the LMS mill  for a few reasons. First, the next largest part I need to make is less  than a third the size of the base and the rest of the smaller parts are  smaller still. These smaller parts will demand precision that I'm not  confident the grizzly machine has. Second, the lab space where this mill  will go isn't that big so that the smaller footprint of the 3960 would  be helpful. Not to mention the quieter operation in the lab and  generally higher quality of the LMS option. Third is obviously cost.  Having the machine and most of the needed tooling together (and as one  line item) for under $1500 will make the approval process much faster  and easier and I'm eager to get started on the project.

Edited to fix an error in the picture


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## David Kirtley (Mar 19, 2014)

What you are showing is well within the cutting capabilities of the smaller machine (I have one down the hall - but the tilting version). It's a nice machine. I do think the G0704 is a lot more machine though. The additional capability of the tilt head does change the work envelope pretty radically.


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## TIGL (Mar 19, 2014)

David Kirtley said:


> What you are showing is well within the cutting capabilities of the smaller machine (I have one down the hall - but the tilting version). It's a nice machine. I do think the G0704 is a lot more machine though. The additional capability of the tilt head does change the work envelope pretty radically.



Thats comforting. Do you find the fact that the handwheels have 62-1/2 divisions annoying? I tend to think in binary fractions these days so I kinda doubt having everything in sixteenths would phase me.


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## David Kirtley (Mar 19, 2014)

TIGL said:


> Thats comforting. Do you find the fact that the handwheels have 62-1/2 divisions annoying? I tend to think in binary fractions these days so I kinda doubt having everything in sixteenths would phase me.




Not really, I don't use the divisions for more than depth of cut. I just set up a dial gauge if I have to but usually just am cutting to a line or center point.

If it is important, you can get the Micromark version with inch divisions or get the kit to swap out for inch or metric.


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## TIGL (Mar 19, 2014)

David Kirtley said:


> Not really, I don't use the divisions for more than depth of cut. I just set up a dial gauge if I have to but usually just am cutting to a line or center point.
> 
> If it is important, you can get the Micromark version with inch divisions or get the kit to swap out for inch or metric.



Nah, I don't expect them to bother me, I just wanted to get someone else's first hand experience because it's a sort of unusual feature. It's a shame DROs are so expensive, I was spoiled by the bridgeport i learned on at school


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## hman (Mar 19, 2014)

TIGL said:


> It's a shame DROs are so expensive, I was spoiled by the bridgeport i learned on at school



First off, hello from a fellow chemist (BS & MA, almost PhD) turned machinist/engineer/tinkerer!


Secondly, for a DRO you might want to check out http://www.hobby-machinist.com/showthread.php?t=21478&highlight=davidh

Davidh sells low cost iGaging DROs, which are not that hard to mount and have pretty good accuracy.  I bought some for my lathe, and have been very satisfied.  You can get X and Y for under $100, plus some of your time and some inexpensive materials to mount them.

See also http://www.hobby-machinist.com/showthread.php?t=10343 for one way to mount these on the mini-mill.


Thirdly, I have an HF mini-mill, and it's just fine to use, but does have some limitations I've run into from time to time.  Chief among them is the distance between the column and the centerline of the spindle.  At very best, I'm limited to about 5 3/4" from spindle centerline to workpiece edge.  The LMS may be slightly larger than my HF, but be sure to check their dimensions! This limits how far "into" a workpiece you can go.  You'll never get to the center of an 18" square workpiece with a mini, though your shorter slots might be do-able. 

In addition, large workpieces require lots of relocation on that small a table, and you have to go through the (slightly laborious) alignment every time you move it. 

Much as I love LMS and their products, of the two mills you're looking at, the G0704 is definitely more suitable for this project. 

Best wishes!


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## kd4gij (Mar 19, 2014)

If you wan't a dro the grizzly G0759 Is the G0704 with a 3 axes dro and only $500.00 MORE. i HAVE THE g0704 AND BEEN REAL HAPPY with it. Only wish Thay had the G0759 when I bought it.


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## Ray C (Mar 19, 2014)

To some extent, the issue of the spindle only servicing the front part of the table can be remedied by using a proper size and style vise.  A vise too large (which is a common mistake) puts the jaws in an awkward location.  Some vises have center-location fixed jaws and some have rear-location fixed jaws.  In some cases, the issue has more to do with the bolt-hole positioning and in such cases, an adapter can mitigate the issues.


Ray 





hman said:


> First off, hello from a fellow chemist (BS & MA, almost PhD) turned machinist/engineer/tinkerer!
> 
> 
> Secondly, for a DRO you might want to check out http://www.hobby-machinist.com/showthread.php?t=21478&highlight=davidh
> ...


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## SENC (Mar 19, 2014)

@wrmiller19 has both (actually the precision matthews version of the g0704), so hopefully he'll be along and can help you... but judging from his comments he has found the PM25 to be of higher quality than the LMS


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## wrmiller (Mar 19, 2014)

Yes I have both, and like both machines for similar and different reasons.

The LMS is just as accurate as the G0704 if you use it as it was intended/within its designed to work envelope (I have the PM25 which is the G0704 with different paint, motor and controller). I consider the LMS one of the best, if not THE best mini-mill. Better motor, larger table, belt drive head, inch leadscrews, and EXCELLENT customer service from LMS. The 20 tpi leadscrews allow easier positional repeatability than the courser ones on the Griz. I have 3-axis glass scale dros on both machines and find it very easy to repeat position on the LMS to a couple tenths (observed on the DRO, verified on a dial indicator). The larger mill will as well, but a more delicate touch on the handwheels is needed.

I never used any end mill larger than a 3/8" rougher on the LMS because frankly, it doesn't have the mass/rigidity to handle anything larger without complaining loudly. I mostly used 1/4" end mills for aluminum, smaller for hardened steel like 1911 slides, titanium, and some of the more difficult stainless steels.

For small delicate work I give the nod to the LMS. Oh, and I highly recommend the air spring conversion from LMS if you get this mill. Positional repeatability increases dramatically on the z-axis with this mod. It also gives a bit more z-axis range. Always a good thing. 

For larger cuts on larger work pieces and using larger end mills up to 1/2" I use the PM. I think of it as the LMS' bigger brother. More mass, more rigidity, more HP, larger table, etc., etc.. But it too must be used within it's designed work envelope. You try taking a full-width pass at a DOC of .5" with a 1" end mill in 4140 on this machine and you will likely at the very least shear the teeth off the plastic/nylon intermediate gear, or at the worst possibly damage your machine or tooling. I have milled everything from aluminum and iron to stainless and hardened steel and have yet to break the intermediate gear. But...I use small(er) cutters and modest cuts. This isn't a BP or Cinci. You need to take it easy and the machine will perform well and accurately.

The Griz/PM has tapered gibs which IMO make it easier to keep things tight and accurate. The gibs on the LMS work just fine, they just need a bit more fiddling to get things to my satisfaction. It (PM) also has a two-speed head that keeps the motor in a better torque range for slower rpm work if that is a consideration. I personally will be modifying the PM to a belt drive soon as I know better than to use large tools that require slow rpms on this machine, and the smaller cutters could benefit from a higher (3-4k) rpm operating range ceiling. (if after doing your base plate you find yourself doing most small delicate work, LMS has a belt drive/bearing upgrade for their mill that doubles the max rpm available)

That's pretty much all I can think of at the moment. If you think of specific questions, feel free to post 'em here or PM me and I'll answer as best as I can.

Bill


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## markknx (Mar 23, 2014)

AS much as a liked my LMS 3960 I had to let it go this year (space slow work ect.) But it was very capable of the work you need to do. that said I your company will spring for the G0704 get it. I say this because your next request from the boss may be for something with a bigger base. If you go with LMS be sure to make the work piece Square that way you can set up stops on one side to realign the part when you have to rotate it. Good luck and keep us posted.


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## TIGL (Mar 27, 2014)

Update:

Since the general consensus seems to be that my 18"x18" plate should be on the upper end of (but still safely within) the capabilities of the LMS machine, I decided to stick with it since having the machine and all necessary tooling as a single line item _dramatically _simplified the corporate approval process. Since maintenance has a nice DTI I should have everything wee need once my pile of aluminum gets here. I would like to have a fly cutter but I suppose that can wait. 

Thanks everybody


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## wrmiller (Mar 27, 2014)

Have fun with your project!

And you might update us occasionally with your progress in the PM/LMS forum. I for one would be interested in how this turns out.  

Bill


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## TIGL (Mar 28, 2014)

wrmiller19 said:


> Have fun with your project!
> 
> And you might update us occasionally with your progress in the PM/LMS forum. I for one would be interested in how this turns out.
> 
> Bill



Thanks, I will! 

One last question, I realized I can get a fly cutter along with the raw materials from MMC. I've never tried to grind my own tool bit so I thought I'd get a premade one. I know I need a left handed turning bit but I'm not sure what style is best for surfacing. Any suggestions?


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## wrmiller (Mar 28, 2014)

LMS has a fly cutter with a pre-ground cutter and a 3/8" shank for around $20

Bill




TIGL said:


> Thanks, I will!
> 
> One last question, I realized I can get a fly cutter along with the raw materials from MMC. I've never tried to grind my own tool bit so I thought I'd get a premade one. I know I need a left handed turning bit but I'm not sure what style is best for surfacing. Any suggestions?


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## TIGL (Mar 28, 2014)

wrmiller19 said:


> LMS has a fly cutter with a pre-ground cutter and a 3/8" shank for around $20
> 
> Bill



I'm familiar with the LMS one and may buy it if I can't find what I need. The reason I wanted to get the one from McMaster is that it will be much easier to get it approved if I add it in with my raw materials rather than writing up a separate application for approval to buy capital goods. That's corporate America for you I suppose 

Edit: The ability to buy preground HSS bits from mcmaster is also helpful since I am a sub novice at that craft


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## toag (Mar 28, 2014)

I had a lms with the tiltingcolumn, great starter machine... but for a work environment I would go witbh the larger one if you can.  now thagt I have a few more years under my belt I would have bought a larger used machine instead of the lms mini mill.  iput the igaging dro's on it which are a great add, and the gas piston also a great add.

But even after all that, its still a small mill, and for 1500 you can get a pretty big used knee mill, andx have alot more capability.


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## wrmiller (Mar 28, 2014)

I am lucky I guess, in that I am able to expense purchases up to 50k. For work.

Now if I could just figure out how to use that for a couple of machines for my garage...  :think1:

Bill



TIGL said:


> I'm familiar with the LMS one and may buy it if I can't find what I need. The reason I wanted to get the one from McMaster is that it will be much easier to get it approved if I add it in with my raw materials rather than writing up a separate application for approval to buy capital goods. That's corporate America for you I suppose
> 
> Edit: The ability to buy preground HSS bits from mcmaster is also helpful since I am a sub novice at that craft


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## TIGL (Mar 31, 2014)

wrmiller19 said:


> I am lucky I guess, in that I am able to expense purchases up to 50k. For work.
> 
> Now if I could just figure out how to use that for a couple of machines for my garage...  :think1:
> 
> Bill



Lucky! That's seriously awesome. 



I'm thinking style 2 but I'd like some confirmation that its the right choice


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## dave2176 (Mar 31, 2014)

TIGL said:


> Lucky! That's seriously awesome.
> 
> 
> 
> ...



Those bits are for a lathe. A flycutter needs to lay or be ground perpendicular the work piece. Install the flycutter, take a 1 2 3 block laid on the table, mark the angle to grind the tool bit and grind. Leave a little relief on the back edge so the cutting edge is the lowest point.

Dave


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## markknx (Apr 1, 2014)

Is this for the fly Cutter? These lookto be turning tools. What is the sorce of  this chart?





TIGL said:


> Lucky! That's seriously awesome. I'm thinking style 2 but I'd like some confirmation that its the right choice
> 
> 
> 
> ...


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## TIGL (Apr 2, 2014)

markknx said:


> Is this for the fly Cutter? These look to be turning tools. What is the source of  this chart?


Its what comes up when I search "Fly cutter" on McMaster Carr. 
​The reason I'm looking for preground tools is because it's something  I've never tried to do before and there is nobody here  in meatspace who  can teach me. I could stumble through it unguided and prossibly come up  with something workable but with this project being my introduction to  so many other aspects of fabrication, one less convolution would be  nice.


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## TIGL (Apr 19, 2014)

Update: I ended up ordering one of style 2 and a blank 5/16 tool bit along with the 2" head. The mill and about 60 lbs of aluminum get here Monday and I couldn't be more excited


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## wrmiller (Apr 19, 2014)

Gotta post pics...  )

Bill


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## TIGL (May 2, 2014)

Hey everybody! The mill and aluminum came in a about a week and a half ago. I've been so busy making chips I haven't had time to post an update 



Mmmmm... tooling


All the best toys come in crates 


in the maintenance shop where it will live until our lab is finished




Left it on the base until I can get/make a better base for it.


Never saw the need for a clamping kit when I was learning on a Bridgeport at school but its been crazy handy on this mini machine


chips, chips


and more chips 


Sadly, the reason that I have time to write this post today. Chris is sending a new board.​


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## markknx (May 4, 2014)

Wow what happened to the board? How was the milling going to the point? As I recall you were going to do a wide plate, is this block just practice or isit for something?Mark


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## wrmiller (May 4, 2014)

Had I known you were going to use that large a cutter, for that long a period, I would have suggested you look at a PM 932 or something similar.

I don't even use a 5/8" end mill in my PM25. The LMS isn't going to last very long at that work load. It simply isn't built to handle it for a prolonged period.

Just my $0.02,
Bill


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## TIGL (May 8, 2014)

Brace yourselves, a wall of text is inbound



markknx said:


> Wow what happened to the board? How was the milling going to the point? As I recall you were going to do a wide plate, is this block just practice or isit for something?Mark



Same project, the block I was working on will have a lug on the bottom that will rest in the slot. 



wrmiller19 said:


> Had I known you were going to use that large a cutter, for that long a period, I would have suggested you look at a PM 932 or something similar.
> 
> I don't even use a 5/8" end mill in my PM25. The LMS isn't going to last very long at that work load. It simply isn't built to handle it for a prolonged period.



I got the new board today and have the mill back up and running. To avoid the overload issue in the future I'm going to be installing an exhaust fan in the main control box and am looking at ways I can alter my design to require less intense machining. Rather than the bunch of U slots and enclosed areas which I would need to painstakingly chip away at, I reworked the parts to only require L shaped notches that are open on the top and side and go the full length of the workpiece (see below). Working in from the side will avoid the heavy load caused by prolonged, full engagement cuts and should really lower the stress on the electronics.

​
That being said, I'm wondering if I can't do better still using a slitting saw to remove the corner with two perpendicular cuts that run the length of the bar. Do you all think the machine can handle it? Not having to turn the whole volume into chips would certainly be less work but it might require more power than I have available.

I was thinking about buying this slitting saw and putting it on this arbor so that I could cut out the the notch and have a 1"x1" bar left over instead of a giant pile of chips. I'd take it slow and not try and do it in a single pass obviously but I wonder if it might not still be more than the mill can handle.


I really appreciate all the advice y'all have given me. Like I said in the OP, this is way deeper than anything I've tried before.


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## JimDawson (May 8, 2014)

If you have one, roughing that out on a bandsaw would be a good start.  That way you just need to clean it up.


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## kd4gij (May 8, 2014)

I agree you need to use a band say to rough that out. A slitting saw would but a pritty havey load on that small mill.


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## TIGL (May 8, 2014)

JimDawson said:


> If you have one, roughing that out on a bandsaw would be a good start.  That way you just need to clean it up.





kd4gij said:


> I agree you need to use a band say to rough that out. A slitting saw would but a pritty havey load on that small mill.



Rats, that's what I was afraid of. Even with a 1mm thick blade?

I have access to a portable horizontal band saw (it's how I've been cutting up the 6' bar I started with) but I'm hesitant to use it on a 4" cut like this. It struggles a bit with the 2.5" square stock so I'd prefer not to double the distance that the blade is engaged.


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## markknx (May 9, 2014)

TIGL, Have you tried a different TPI blade O the saw? Is this a 4 x6 style like HF sells? if so it should handle it but you would need at most 10-14 vari TPI. But 8TPI would be great if you can find one. Even carefull use of a hacksaw may be quicker.  Mark


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## TIGL (May 9, 2014)

markknx said:


> TIGL, Have you tried a different TPI blade O the saw? Is this a 4 x6 style like HF sells? if so it should handle it but you would need at most 10-14 vari TPI. But 8TPI would be great if you can find one. Even carefull use of a hacksaw may be quicker.  Mark



Knowing that I'd be making these wide cuts I got the fewest tpi blade I could find (12 I think). It still felt kinda rough :-/


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## kd4gij (May 10, 2014)

The 12 tpi should cut it use wd40 to keep the cut lubed.


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## John Hasler (May 10, 2014)

TIGL said:


> Knowing that I'd be making these wide cuts I got the fewest tpi blade I could find (12 I think). It still felt kinda rough :-/



My 4x6 eventually cuts anything I can fit into it.  Use the lowest speed, not too much pressure, and lots of lube.  One 4" cut or four 1" cuts are the same to the saw as long as you don't force it.


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## TIGL (May 12, 2014)

John Hasler said:


> My 4x6 eventually cuts anything I can fit into it.  Use the lowest speed, not too much pressure, and lots of lube.  One 4" cut or four 1" cuts are the same to the saw as long as you don't force it.





kd4gij said:


> The 12 tpi should cut it use wd40 to keep the cut lubed.



I bought a gallon of WD40 and put it in a spray bottle to use as general cutting fluid. I've used it a lot for endmilling and bandsawing but it still didn't leave me with a great feeling. I'll try it but I suspect I'll end up milling the thing out instead. I also need to make a version of that part that is 12" long so no way I could cut that with the bandsaw. 

Shame really. The slitting saw would be perfect if the machine could handle it :-/


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## AlanR (May 12, 2014)

TIGL said:


> Shame really. The slitting saw would be perfect if the machine could handle it :-/


A 2.75" saw can't cut to 1" on an arbor which is 1.25" in diameter. Max would be less than .75", I was going to suggest multiple passes but it won't work anyway.

I don't like the stepped arbors, the runout is too much.

To be honest that machine is too small for what you want to do.


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## TIGL (May 12, 2014)

AlanR said:


> A 2.75" saw can't cut to 1" on an arbor which is 1.25" in diameter. Max would be less than .75", I was going to suggest multiple passes but it won't work anyway.
> 
> I don't like the stepped arbors, the runout is too much.
> 
> To be honest that machine is too small for what you want to do.



I would absolutely be doing it in multiple passes, it would be crazy to do it any other way on this size machine (its pretty much crazy regardless). I thought I had math'd it correctly but now that you point it out, its obvious that saw is too small to do a 1" DOC. I suppose I could finish the cuts with the band saw but then why not use the bandsaw for everything? I could also cut a .75x.75 section off the corner and take the last .25 off with an endmill. That would also make the runout less of an issue. Hmmmmmmm....

Yes, sadly it is probably too small. Live and learn I suppose :-/ Even with the additional cooling from a 120 CFM fan you think it would be too much?


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## AlanR (May 12, 2014)

TIGL said:


> Even with the additional cooling from a 120 CFM fan you think it would be too much?



Never know till you try, check the temps as you go. You can buy a temperature measuring gun from Harbor Freight.


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## TIGL (May 12, 2014)

AlanR said:


> Never know till you try, check the temps as you go. You can buy a temperature measuring gun from Harbor Freight.



Very true. I can probably get a IR thermometer from maintenance but I'm still nervous. I don't think Chris would send me a third board so I need to make sure I don't fry this one too. At what sort of temperature should I start to get worried?


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## JimDawson (May 12, 2014)

TIGL said:


> Very true. I can probably get a IR thermometer from maintenance but I'm still nervous. I don't think Chris would send me a third board so I need to make sure I don't fry this one too. At what sort of temperature should I start to get worried?



I just looked up specs for a motor controller mosfet, the absolute maximum junction temperature is 150 C, it looks like normal operating temperature might be in the 70 to 90 C range.  Based on that, if the heatsink is getting close to 100 C I would start shedding some load.  I'm surprised that the controller doesn't have a thermal shutdown, most of the controller IC's have that built in.

This advice is my best guess, and worth exactly what you paid for it.)

another thought

Run it a medium speed, unloaded, for a while to get a base line reading.  Then try it under a light load.  Take severial readings under different conditions to see what 'normal' is.


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## TIGL (May 13, 2014)

JimDawson said:


> I just looked up specs for a motor controller mosfet, the absolute maximum junction temperature is 150 C, it looks like normal operating temperature might be in the 70 to 90 C range.  Based on that, if the heatsink is getting close to 100 C I would start shedding some load.  I'm surprised that the controller doesn't have a thermal shutdown, most of the controller IC's have that built in.
> 
> This advice is my best guess, and worth exactly what you paid for it.)
> 
> ...




Thanks for the ideas. I ended up ordering the saw so I'll see how it goes. Hopefully the cuts I take won't have to be so small that it kills any time saved from not having to turn the whole thing to chips


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## AlanR (May 13, 2014)

TIGL said:


> Thanks for the ideas. I ended up ordering the saw so I'll see how it goes. Hopefully the cuts I take won't have to be so small that it kills any time saved from not having to turn the whole thing to chips


In reality the cuts depend more on the table feed rates, slower feed, less spindle power.  Do you have a power table feed on that machine? If you don't you should get one.

I just got a nice 1" arbor, so much better than the stepped ones. I thought about making one but I couldn't have made one as good as the one I bought, they're not cheap.


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## kd4gij (May 13, 2014)

Get a good quality 1/2" roughing endmill. That should help you out.


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## TIGL (May 14, 2014)

I am thinking about getting a power feed but do not currently have one. It would probably make this project much easier. I suspect I will need one when I move to the foot long version of this part




kd4gij said:


> Get a good quality 1/2" roughing endmill. That should help you out.



I ordered two of these from McMaster along with the saw and arbor so if the saw proves impractical I'll use them


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