# CNC Gantry Mill/Router



## gerritv (Sep 23, 2020)

I started building this in Feb this year after seeing Stefan Gotteswinter's Stepmores SM4040 in action on YT. The machine is just the right size for my perceived needs.

Built up from 1/8" wall 2x4, 2x2 and 1x2 steel tube. Joints are with T Bolts, furniture style. made from 1/2" CR steel. Main assembly is with 5/16-16 SHCS.
The Z axis is built up of aluminum plate, X Axis is 6x2 aluminum U Channel salvaged from Univac II tapedrive from 1958 (I worked for Univac at Ont Hydro and helped scrap the Univac II's they had in 1968) A true justification for 'you never know when you might need it' hoarding.
Ball screws are Thomson 1/2 salvaged from a 1980's digitizer from Bata Shoes as are the Y axis rails and bearings. 
Spindle will be water cooled ER20 via Aliexpress.
Software is Pathpilot using a Mesa 7I92h and an old PMDX-132 bob.
Should be running sometime in October at present slow rate of progress.


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## Johnwa (Sep 23, 2020)

That looks pretty solid!  What are you planning to use it for?


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## RobinHood (Sep 23, 2020)

Very nice.

is that a heat treating oven on the floor showing in the picture just below the gantry stepper motor?


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## gerritv (Sep 23, 2020)

Initially to make reproductions of displays for a Univac II console panel that my brother and I are 're-animating'. 12 display modules, each with 10 thin edge lit acrylic with a number engraved on it.
Then back to the Rudy Kouhoupt marine engine. No doubt along the way I will be making fixtures on it.

There are some other engines on my list that would benefit from CNC. My small horizontal mill is not up to a lot of the required machining, largely due to everything being a workholding challenge on it.

Gerrit


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## gerritv (Sep 23, 2020)

Yes, I built that based on plans from this site: https://dcknives.blogspot.com/p/electric-forge.html Great for shop made gear cutters, counterbores etc.

Gerrit


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## PeterT (Sep 23, 2020)

Nice! Keep those progress pics coming!


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## Janger (Sep 24, 2020)

Glad you're here Gerrit this is good stuff.


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## Tom O (Sep 24, 2020)

That’s a good site.


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## gerritv (Oct 10, 2020)

It is sooo close to running. But house and yard has prioirty, and helping a friend build a new fence/gate. Next week is clear so expecting to have this running on Pathpilot very soon.
After a ton of layout, pin-prick followed by centre punch I am seriously impressed with what you can do on a drill press. Almost nothing on this build was done with my milling machine except cross drilling the t-bolts. The 16 holes for the bed subplate all lined up!
Shop made counter bore did the trick to get the SHCS recessed.

gerrit


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## gerritv (Oct 12, 2020)

And its moving. Spindle arrives next week which is when the real fun begins.





Gerrit


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## gerritv (Oct 17, 2020)

And we are now cutting. Lots of details left to work on but I know the machine works.


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## PeterT (Oct 17, 2020)

Way to go. 
Maybe you mentioned already but what is the wattage of your spindle motor?


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## gerritv (Oct 18, 2020)

It's 2.2kw ER20 water cooled


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## gerritv (Oct 18, 2020)

I really want to believe this number:


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## RobinHood (Oct 18, 2020)

I guess you are measuring TIR of the endmill shank in your spindle you got off AliExpress?

I would say that that is very good. My 1968 BP mill gets 2 to 2.5 tenths TIR at the endmill shank with an R8 to ER32 adapter and appropriate collet.


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## PeterT (Oct 18, 2020)

I could be. But an appropriate prior check step is remove the collet & EM shank & measure the ID cone. If you get a similar number you are probably good. But by introducing extra elements all you read is the collective whole. Potentially you can have cancellations or exaggerations depending on how they align/misaligned.

For example lets say we know for sure spindle ID cone is off 0.001". And collet/shank is also off by 0.001". Put them together one way minimized & they cancel 0.000" Put them together phased a different maximized way & you get 0.002". Anything in between yields different relative number. 

I've heard of some good numbers on spindles in that caliber. I've also read some amazing numbers in the cheapo 500w spindles & then they show cheapo skateboard bearings in there so hard to visualize, or will it stay that way.

I'd like to see how you circulate cooling water & related issues. Is it just tap water & waste system you just dump the bucket or certain additives or...?


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## gerritv (Oct 18, 2020)

Yes I  know there are correct/best practices for measuring runout, however I wanted a sanity check before going any further. My manual mill has .006" on a good day so already happy that this is possible.
Water will be dumped/recirculated in a large square pail. The motor doesn't really hewat up much so far so not worried too much. I do owever have to wiat for the correct voltage pump to arrive, they sent a 220v one, and no 220 in the shop.

In the meantime sorted out a bunch of issues and did some test cuts in al and cold rolled steel. Very pleased. Lots more to do before I run any programs though.


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## Tom O (Oct 18, 2020)

Looking good have you tried tapping on the cutter to see if it improves the run out? NYC did a video on it.


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## gerritv (Oct 14, 2021)

And now here we are, the machine is useful:





Gerrit


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