Author Topic: First CNC mill  (Read 9381 times)

Offline ChriX

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First CNC mill
« on: December 29, 2013, 01:49:23 PM »
Hi all. Looking for a bit of advice on where to start with a CNC mill. My aim (at least to start with) is to be able to make brass nameplates. These will have quite deeply cut lettering so a lot more than just an engraving.

Currently I am looking at getting one of the chinese mini mills - probably an X2 size, but then need to convert it to 3 axis CNC. I will get an R8 spindle so I can share tooling with my Bridgeport. I am not too sure where to start - is there a good set of conversion plans I should follow? Seems to be a few options. Is there a good supplier in the UK that has all the bits; ballscrews, controllers/drivers, power supplies and motors?

If anyone can send me in the right direction that would be great.  :beer:

Offline spuddevans

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Re: First CNC mill
« Reply #1 on: December 29, 2013, 02:04:09 PM »
I don't know if this helps, but I documented my CNC conversion here http://madmodder.net/index.php/topic,3535.0.html

I bought my ballscrews off ebay from China, steppers and drivers came from Arc Euro Trade (both were on sale at the time, saved quite a bit) and I made all the brackets before starting the conversion (it is my only mill)


Hope this helps, don't hesitate to ask for any other info, if I can remember it I'll tell it  :lol:


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Pete.

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Re: First CNC mill
« Reply #2 on: December 29, 2013, 04:12:56 PM »
I saw that homeandworkshop in Sidcup had a couple of Denford Microrouters in last week. Might be good for a conversion, motors, steppers and ballscrews all in place.

Offline Brass_Machine

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Re: First CNC mill
« Reply #3 on: December 29, 2013, 07:04:53 PM »
Hi Chris,

If you go with the X2, see if you can find the SX2. LMS sells them in the States as a Solid Column mill. It loses the highly flexible titling aspect of the X2. If I had the money, I would just buy the Grizzly G0704. I think it is equivalent to the warco WM16?? Even then, the WM14 looks like a sturdier mill.

I personally have an X2. I bought the conversion kit for the solid mount column.

Check out Hoss's page on converting a X2 Here

Eric
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Offline ChriX

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Re: First CNC mill
« Reply #4 on: December 30, 2013, 09:40:36 AM »
Thanks, looks like there is a lot of information around for the X2. The one that Arceurotrade sell (here: http://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Milling-Machines/Model-Super-X2-Plus-Mill/SIEG-Super-X2P-HiTorque-Mill) seems to match the LittleMachineShop one. I was hoping to find a used mill to convert rather than buying new. Seems like if I am rebuilding it and putting new screws in anyway there isn't much to lose by going with a used machine.

Tim - you mention in your thread that you weren't sure if the 350Ncm motors were going to be enough without pulleys; did they work out OK in the end?

As always would like to go for a bigger machine but trying to keep costs down as it's only an experiment to start with.

Offline philf

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Re: First CNC mill
« Reply #5 on: December 30, 2013, 01:11:03 PM »
Tim - you mention in your thread that you weren't sure if the 350Ncm motors were going to be enough without pulleys; did they work out OK in the end?

Chrix,

My machine is much bigger and heavier than an X2 and works fine with 3.1Nm (310Ncm) motors driving the screws (15mm dia x 5mm pitch) directly (i.e. no belts). I got my motors and drivers from http://www.cnc4you.co.uk/ (Usual disclaimer.) I use less than the rated current and 8 microsteps/division. For my Z Axis I do have a 1:3 belt drive.

Sometimes a belt drive can be neater and more compact. Decent backlash free shaft couplers aren't cheap and a pair of pulleys and a belt aren't much different pricewise.

Cheers.

Phil.
Phil Fern
Location: Marple, Cheshire

Offline spuddevans

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Re: First CNC mill
« Reply #6 on: December 30, 2013, 02:04:23 PM »
Tim - you mention in your thread that you weren't sure if the 350Ncm motors were going to be enough without pulleys; did they work out OK in the end?

Hi Chris,

Yes they were plenty strong enough, I have direct drive on X and Y and a 2:1 ( I think :scratch: )reduction on Z, though I think the stepper would have been strong enough to do 1:1.  I have never pushed the machine hard enough to miss any steps, but I have bogged the cutter down with Ali chips and then the spindle motor drive has cut out and then the steppers have tried to carry on breaking a 1/4" endmill before skipping any steps, so I'd say that they are plenty strong enough.


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Swarfing

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Re: First CNC mill
« Reply #7 on: December 30, 2013, 04:23:52 PM »
Chris consider the 45 range of mills as a good starting base. Chester do the lux to this size and warco do the GH etc etc. this the pm45, rm45 of machine. The advantage is the table size without being over the top. I'm converting  my Arboga at the moment and would not recommend that at all.
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Offline raynerd

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Re: First CNC mill
« Reply #8 on: December 30, 2013, 05:27:56 PM »
Chris, not sure where in the world you are but I have an x2 needing work sat on my bench waiting to be converted to CNC. It'll not happen as I'm too busy and get barely any time for building projects which is what I need to start focusing on! It does need work but email me if interested chris@raynerd.co.uk 

I upgraded to an x3 last year when one came up cheap and after a few problems with the spindle on this x2...it has been sat on the work bench since! The x axis is already converted to CNC control as used a stepper as a fancy power feed in conjunction with a CNC rotary table for clock wheel cutting.

Just a thought..... Otherwise it will get converted by me at some point

Chris

Offline ChriX

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Re: First CNC mill
« Reply #9 on: December 31, 2013, 06:48:23 AM »
Paul - too big for this experiment! If it all goes well maybe I will treat Bridget to some ballscrews in the future!

Chris - have sent you an e-mail.

Offline raynerd

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Re: First CNC mill
« Reply #10 on: December 31, 2013, 04:09:06 PM »
Got your email chris. I'll reply tomorrow when I'm in my workshop.
Chris

Offline Swarfing

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Re: First CNC mill
« Reply #11 on: January 01, 2014, 07:47:44 AM »
Sounds like you could be onto a winner with Chri's offer, happy new year guys
Once in hole stop digging.

Offline Jonny

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Re: First CNC mill
« Reply #12 on: January 01, 2014, 02:24:59 PM »
consider the 45 range of mills as a good starting base. Chester do the lux to this size and warco do the GH etc etc. this the pm45, rm45 of machine. The advantage is the table size without being over the top.

I certainly wouldn't recommend at all for CNC conversion though on paper its far more robust.
The problems are bed flex due to it being too long for the foot print its on along with the actual bed not deep/strong enough. Ok for small parts used over a small area, but start extending available range with any accuracy is out the window.

Secondly the upright column gibs and head needs tightening up 'tight' at each height position. This is due to the shear weight of the geared head. At best you would have play in the gibs even brand new, as the gibs are nipped up it affects the tramming dependant how tight or not at all. ie nip up bottom first you would see the head tilt left to right and pull away at cutter from column. Nip top up it will do same again and bottom tightening up again.
May be ok if gears taken out and converted to belt and pulley or direct drive with higher speed than 1250rpm, way too slow. I reckon I can save 3 to 4hrs a day on the stuff I do, just takes an eternity like 13hrs for a 5hr job.
Whilst at it beef up the bearings to manage more than 1500rpm to a more usable 2000+rpm. Some US companies mod these and can go R8.

Only a problem for manual use like all Chinese machines the leadscrews wear at amazing rates. My elevation had over 2 revs backlash! Powered head transfer boxes £244 which the motor mounts to.
Again not cnc the quill wears the casting away oval at the back where theres little bore. Creates problems centre finding! Soon as quill locked you've lost centre.

If it were me I would take Chris up on his offer even though its a lighter faster machine.

Offline JohnHaine

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Re: First CNC mill
« Reply #13 on: January 21, 2014, 06:10:29 PM »
I started off modding an X1, but decided after a while that it was clearly not a good basis for a cnc machine, so sold to a friend.  Bought a Denford Novamill without electronics off eBay, spent not much more than £100 on drivers from HK, brilliant machine, vastly better than an X1 or X2.