New CNC Router - Welded steel

I'm finally getting around to building a new router.

I've previously built one of my own design which had 900x375mm cutting area. It was based on SBR16 rails with ballscrews (single screw on X). Made of 25mm plywood and aluminium extrusion. Unacceptable flex and racking, I've never been happy with it.

So after plenty of reading and research, I've come up with my replacement design.

I was initially going to bolt everything together and painstakingly level. I've since bought a welder and will be using that.

Design:
Welded steel construction
Dual drive on gantry
Cutting area of greater than 1220x610mm (quarter sheet) - will be ~1250 by ~650mm in reality
Travels ~1250x675x200mm
Self levelling epoxy for rail mounting (probably West System 105 + 209)
Linear profile bearings
- already have 830mm long 20mm rails for the Y axis (short axis)
- 15mm new Hiwins for X (long axis, 1500mm along gantry) and Z axis
15mm ground ballscrews with 20mm lead for Y axis (already have)
16mm rolled ballscrews with 16mm lead for X and Z axis (new, SFE1616)

I have decided to go for a wide machine, with the gantry running the longer axis for two reasons:
1. It works better in the vast majority of spaces as it can be loaded from the front.
2. I already have a very nice pair of ground 20mm lead ballscrews with great bearing blocks.
The steel gantry will be stiffer than 3060 8020 used in CNCRP machines, and I believe will be adequate.

Maximum workpiece height is ~100mm
The Z axis travel has been designed to reach the table with 20mm tool stickout, and to clear the top of a 100mm piece of work with 80mm of tool stickout. The spindle will be adjustable up and down if I need to work with very short tools or very long tools.

Overhang over front of machine for vertical machining (65mm thick pieces) and a 4th axis (should be able to machine 150mm diameter by ~1m long)

The table top will be a layer of ~30mm MDF covering full area, with T slots and Tee Nuts, then another ~18mm piece same size as cutting area as sacrificial board.

The steel:
Large Y axis rails are 200x200mmx6mm RHS.
The Gantry is 200x200mmx6mm RHS with an unsupported span of ~1400mm.
The bearers under the table are 150x50x3mm RHS
I'll likely put a strap joining the bottom of the bearers to box it all up.
Without the stand, it looks like the machine will weight >160kg (352lb)

 

Yesterday I got all the steel cut for the router (including a stand, not shown).

Today I squared the ends and then got welding.
The beauty of this design (in theory at this point) is that the epoxy levelling means precision is not important at this stage. Within a couple of mm is fine.

This is my second welding project. The first project I ever welded is the mill stand that is underneath and being used as a temporary welding table.
I'm not much of a practicer, so I just had at it, and my welds are improving fairly quickly. The flat weld on butt joints is going well. Fillet welds are still very hit and miss.

Steel cut

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Welding in progress - sorry for the crappy phone picture, was welding till it got dark.

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Mill stand

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That construction looks like enormous overkill. Keeps with the spirit that is OCAU ;-) I'm also building a cnc machine atm, using the shapeoko 2 kit and design as a basis for a 1000x1000 machine.

 

Overkill is great for equipment like this.

Look at any really old workshop machines and they will likely be large, heavy cast iron frames as they didnt have the technology to do lightweight aluminium and welded space frames back then. It made transport difficult, but once they are in position they are stiff, accurate and durable. A lot of machinists still love them.

 

yep, I've found in workshops that the older the machine, the more robust and reliable it is.

https://www.youtube.com/watch?v=RXIRbazT2Rs

 

Hey pippin, just found this

 

Thanks for the interest guys.

Progress:

Stand welded and first coat of paint on:

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Uprights are 75x75x3mm
Horizontals are 50x50x3mm
Slats are 25x25x2mm
Weight ~65kg
Getting it up on to the router by myself to mark and drill the mounting holes was tricky to say the least. It was fine to move around until I welded the slats in. Before I could stand in the middle, squat and lift from the horizontal in the middle and get a fair bit of height. With the slats I can get in there and lift from the top horizontals and move it around, but can't squat down to lift from the middle so can't get the height.
*Just* managed to get it on top of the router without killing myself, though my neighbour was hanging out their window asking if I needed help.

Paint is $10 a litre ALDI metal paint. Read lots of good things. I'm pretty happy thus far, goes on pretty well. Stand has just been brushed.

Gantry painted:

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200x200x6mm 1.6m long. Weighs ~55kg.
I forgot to prepare the new roller (removing loose fibres) so ended up with the first coat covered in fibres
Scotchbrite pad and a quick rubbing got rid of most of them when the first coat was dry.
Got some more with the second coat, but not as bad. Will likely give it a light sand with fine grit paper.

Then I faced the problem of how to move a 55kg 1.6m long beam that has paint that is just tack dry - I can't just pick it up and move it like I did to get it there.
So I walked it:
You'll notice it's on a 2x4 between the two saw horses (BTW these are from Bunnings and are shit, do not recommend, very warped and uneven). There is ~a foot of length spare.
1. Advance the back saw horse so it is close to the end of the gantry.
2. Advance the front saw horse so that it is at the front end of the 2x4
3. Slide the 2x4 forwards (making sure you don't drop of the back saw horse)
4. Rinse and repeat.
Took a little while but worked.

Next up is a few final bits of welding and grinding on the main router body and then it gets painted.

 

Looking good, i like that aldi black paint too, done my benches with it

 

Got some more done today.

Main thing was preparing the gantry for epoxy pour, which included building the dams and doing an initial pour to seal any small gaps.


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Gantry dams built. The form in the middle is to reduce epoxy needed and create space for the ballnut to travel. It's going to be quite tight fitting the ballnut in.


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As expected the area around this end was a problem. The wooden block in the middle is sitting in a cut out for the stepper motor. I had some leaks around here.

So I quickly grabbed the blutack (only putty / mouldable I had on hand) and had at it:

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In retrospect I think it would be easier to do the initial leak sealing pour with fast setting epoxy instead of slow (I'm using West System 209 extra slow hardener)

Hopefully do main epoxy pour tomorrow. Have to go buy a heat gun for the bubbles.

 

Epoxy pour seems to have gone ok from a quick peek. I had some problems with an oily residue on the surface, likely because I didn't thoroughly clean before the pour. It's visible, but I hope hasn't affected the surface flatness. Going to leave it for a full week before I pull apart the form work.

Today I got the aluminium I need for various parts, and firmed up the CAD model.

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I also moved the router body. It weighs about 120kg at present and is not an easy shape to move around. I'd been scratching my head on how best to move this without hassling 2-3 other people to just carry it (I'm going to need to move it a few times). Then I realised I can very easily make a cart:


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Couple of timber beams with a few screws, and some casters I had lying around.


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I had the router upright from painting. I moved it to the front edge of the table, and put two saw horses, lined up with the big beams. Some rags to protect the paint.


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A controlled topple / slide forwards on to the saw horses.


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Moved the table back and rolled the cart in to position.


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Controlled descent on to a couple of cushions. Then I pulled them out (Note, you've got to be comfortable lifting a third to half the weight to get the cushions out, if you have a bad back I'd suggest other techniques).


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Tip it upright fully.


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And we are rolling.

Somehow I don't think it's going to be as easy working against gravity...

 

A rolling workshop crane probably would come in very handy if you could beg/steal/borrow one.

Ratchet straps is another way but I cannot say I recommend at all!

 

Yeah, but unfortunately I don't know anyone with one, don't have a trailer and not a huge amount of room to move in the shed. I do dream though.

 

Came here expecting a network router

 

Awesome work mate.

 

My work is getting a Biesse Rover B (very large, 5 axis CNC) so it's great to see someone build one from scratch! I can certainly appreciate the complexity of it!

Best part is, looks like you have built it to a much higher std than is required, which should result in a stable, reliable machine.

Is it mainly sheet work you're planning on doing on it?

 

Thanks for interest guys.

Max size under the gantry is going to be ~100mm high. So can handle sheets and some other objects.

I'll have a 4th (rotary axis) on the front, which should be able to swing 150mm diameter by about 1.2m long. I'll also have mounting on the front for boards held vertically to machine the ends.

 

I did see the 4th there looks great

The large steel should help (bar the lower rapids accel/decel) with the only the linear rails being the bottleneck for rigidity. And you can always upgrade those in the future. For aluminium and softer material you'd cut it like butter with a nice spindle. Any more info on the 4th? Are you building that too?

 

The NSK / Hiwin rails I have should be rigid enough, it's amazing what these 4 row bearing rails are rated for.

4th axis is to be decided. Probably build one myself, but fairly simple.

I've converted a benchtop mill to CNC, so that takes care of metals for me. Will only need the router for aluminium that's too big for the mill cutting area.
I'm just using a Chinese high frequency spindle, so that would be quite poor for metals. When it dies I'll look at better quality options.

 

Get a cheap engine hoist, you would be amazed how universal it is.
I move my 300lt air compressor, wood saw, dexion racking with it.

 

Yeah It'd totally be rigid enough for alu You'd be pushing the limits of the china special spindle way before you'd start getting any serious load conditions on the bearings.

I love it when I can watch the whole project unfold, keep up the good work.