[pippin88]

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.

matth's very simple but elegant frame design spurred me on.
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 ~6750mm 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.
I'd have like to go a bit bigger, but minimum order length appears to be 8 metres of steel. At best I can only use 2.5m (this project and a lathe)

Maximum workpiece height is 140mm
The Z axis travel has been designed to reach the table with 20mm tool stickout, and to clear the top of a 140mm 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 ~19mm MDF covering full area, then another ~19mm piece same size as cutting area.

The steel:
Large Y axis rails are 150x150mmx5mm RHS.
The Gantry is 150x150mmx5mm 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.
I'm planning to order the steel next week.
Without the stand, it looks like the machine will weight >160kg (352lb)

Not shown is a stand that will be made out of 50x50x3mm steel predominantly.
It will have uprights at the machine corners.
There will be a full width bottom shelf. Below the table will be some drawers and area for electronics.

Not shown in the pictures are the X and Z ballscrews, motors etc.

To be worked out
Mounting of the Y axis ballnuts to the end of the gantry beam - I'll probably machine a block that runs between the ballnuts and into the end of the gantry.

Input is appreciated.

[pippin88]

While it's slightly more work fabricating, I'm leaning towards the design revision below.

It will make ballnut mounting easier, and reduce some clearance issues from the high gantry sides.
The table bearers now butt on to the Y axis beams.

Thoughts?

I find it a little annoying having all the space at the back of the table under the gantry that I can't reach with a cutter - but I think being able to cut vertical pieces and add a decent 4th axis outweigh this. Maybe I'll use it for tool storage or something.

[scedward]

In the second revision, you moved the Y rails to be butt welded to the base pieces. Its obvious why you did this, to make room for the additional bracket under the gantry. In my opinion, it is going to be much more difficult to align and weld all those pieces straight and square in that configuration. I would consider using a different profile of steel than the 150x50. 100x50 perhaps, and sit the Y rails on top of the base pieces? In other words, assemble it the same way you did the first revision, only using shorter steel to span the 4 ft width.

FWIW, YMMV....and by the way, I like the design. I've been pondering a similar 4x2 design myself. Though that 6" (5.9") tube for the gantry is gonna be nice and stiff, it sure takes up a lot of room to the rear.

-Scott

[pippin88]

Scott,

Thanks for the comments.
I agree welding will be a bit more difficult.

I'd worked my original design on 150x100 Y beams (laid with the wider part horizontal), then managed to do the deflection calculations on 150x150, and 150x50 for the cross beams. I like the stiffness of 150, particularly for the long span.
I priced 150x100 just for the Y beams, but it would cost me the same as 150x150 because I wouldn't be buying a full length.

I think I'll lay the cross beams on top of a 75mm piece of material at both ends and then have the Y beams clamped against the ends for welding.

[pippin88]

Looks like I'll be able to pick up a piece of 200x200x6mm for the gantry for a very good price, so I'll be going with that.

Working on the stand design. Haven't built a welded stand before, so any tips are appreciated.
Uprights are 75x75x3mm. They'll have a mounting plate welded on top that the router will bolt to. On the bottom they'll have a plate welded with a hole for height adjustable legs.
Cross bars are 50x50x3mm. I'll have some more bars in the middle, maybe 50x50, maybe 25x25.

[pippin88]

Advice please on ballscrew lead please.
I have 2x secondhand ground 20mm lead screws.
I need:
1400mm screw for gantry
300mm screw for Z.

I've priced screws:
10mm lead RM1610
10mm lead RM2010 = 1610 + $20
16mm lead SFE1616 = 1610 + $60

The SFE1616 ball nuts are more expensive ($48 each), and double nuts are not available, meaning if I find backlash a problem it's extra cost again. They also look difficult to do a double nut arrangement.
So I'm leaning towards the 10mm lead screws.

16mm screws with 1350mm between bearings have a critical speed of ~1000rpm, which equals 10m/min.
20mm screws have critical speed closer to 1200rpm, but that's starting to get a bit high for steppers.

Thoughts?

[pippin88]

Well I got some 200x200x6mm RHS for a steal (less than $1 a kilogram). So I'm using that for the gantry, and for the side beams.
I'll still use 150x50x3 for the cross beams (table bearers).

The question comes on how to orientate this now.

I can have the 200 beams sitting proud on top (50mm above the 150mm surface). This has the advantage of shorter supports / risers for the gantry. Less cost in materials and probably stiffer.
The disadvantage is a much more difficult epoxy job as I have to link both beams

Or I can have the top flat (with the 200 beams 50mm proud underneath). This has the very large advantage of a single epoxy pour to get a flat surface. But requires gantry risers 50mm taller than the first option.

In the attached images, epoxy is represented in green.

[pippin88]

Well, I got all my steel in. Now to cut it up and start welding.

I've also got to decide what to do with steppers.

I'm redoing my lathe at present also.
I'm going to use LinuxCNC with a mesanet 7i43 FPGA hardware step generator.
I need 4 drivers for the basic router movement, but I also want a rotary (4th) axis, so I need an extra driver.

I've got:
3x 387oz-in steppers (Voltage: 50V Max, Current: 3.5A, Inductance: 2.8mH)
A G540.
3x 280oz-in steppers (8 wire http://www.probotix.com/specs/HT23-280-8.pdf) that I can wire bipolar parallel.

I need:
One more stepper - will get another 387oz-in I think.
One extra stepper driver
- Any suggestions on stepper driver?
- I have a 5amp 570oz-in stepper on my mill currently (under) driven by my G540, so I'm tempted to get a driver that will take full advantage of this stepper.

I'm looking very seriously at a CWD556 - it appears to be the exact same as a Keling 5056D, but is available quite cheaply. Does anyone have any experience with this driver?

So I'm tossing up whether to put 2x 280oz-in in dual drive to move the gantry on the router, and then use 2x 387oz-in on my lathe. Or use the 387oz-in on the router and the 280oz-in on the lathe
Gantry is likely to weigh 100kg (220lb) all up.
Dual driven with 20mm ballscrews.

(I'll be building an electronics 'cartridge' so that I'll use the same drivers and power supply for mill, lathe, and router. Just remove power and pull cartridge, plug in to next machine and plug in power).

[UA_Iron]

Well, I got all my steel in. Now to cut it up and start welding.

I've also got to decide what to do with steppers.

I'm redoing my lathe at present also.
I'm going to use LinuxCNC with a mesanet 7i43 FPGA hardware step generator.
I need 4 drivers for the basic router movement, but I also want a rotary (4th) axis, so I need an extra driver.

I've got:
3x 387oz-in steppers (Voltage: 50V Max, Current: 3.5A, Inductance: 2.8mH)
A G540.
3x 280oz-in steppers (8 wire http://www.probotix.com/specs/HT23-280-8.pdf) that I can wire bipolar parallel.

I need:
One more stepper - will get another 387oz-in I think.
One extra stepper driver
- Any suggestions on stepper driver?
- I have a 5amp 570oz-in stepper on my mill currently (under) driven by my G540, so I'm tempted to get a driver that will take full advantage of this stepper.

I'm looking very seriously at a CWD556 - it appears to be the exact same as a Keling 5056D, but is available quite cheaply. Does anyone have any experience with this driver?

So I'm tossing up whether to put 2x 280oz-in in dual drive to move the gantry on the router, and then use 2x 387oz-in on my lathe. Or use the 387oz-in on the router and the 280oz-in on the lathe
Gantry is likely to weigh 100kg (220lb) all up.
Dual driven with 20mm ballscrews.

(I'll be building an electronics 'cartridge' so that I'll use the same drivers and power supply for mill, lathe, and router. Just remove power and pull cartridge, plug in to next machine and plug in power).

What cutting velocities are you planning on running? 110kg driven by two lead screws + motors (high efficiency) parallel with gravitational forces with linear guides/bearings should not be that tough. Find the torque curves of your motors vs RPM's, horizontal loading, and cutting forces and make the comparison from there. If you can calculate the forces needed then upsize the motors 50-100% (no more, no less unless you significantly test it). The two motors may not be too far off from each other at these parameters. Be sure to factor in microstepping etc, this will eat into your torque curve.

[pippin88]

I ended up ordering a Leadshine DM556 driver. Upto 50V and 5.6amps.
I'll order another 387oz-in stepper

Just received my new Hiwin linear rails, and my 16mm lead ballscrews, as well as come couplings from BST Automation on aliexpress.
I'm very happy with my transaction with Fred from BST. Good communication.
I ended up with H class precision and ZA preload on the rails.

[pippin88]

Progress, and proof I'm not all talk.

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.

[LeeWay]

That is looking good.
When you take the time to grind your welds flat like the mill stand, you can tell what kind of penetration you are getting. Prep means a lot. Angle the ends of the tube so the bead can really get into it.
I am no welder either. I did take a few classes in school, but many moons ago. I have a little wire feed I use for really light weight stuff. Then a Lincoln 225 for everything else.
Old school, but you get the right rods and you can make some gorgeous welds with it.
Looking forward to the rest of the build.

[pippin88]

Thanks for the interest guys.

Progress:

Stand welded and first coat of paint on:
(See attachment)

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:
(See attachment)

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 :thumbdn:
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 ****, 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.

[MadeInTheShed]

Looking good! Thats one solid machine!

I know what its like to try and manouvre heavy large items alone. My wife and daughter are ussually not a huge help altho I give them full marks for trying. Should have seen us putting in a steel beam in our roof to support a sagging ceiling! I think back now and laugh about it. Not then tho!
I ussually knovk together temporary trolleys or frames to help with this and have used the walking on saw horses quite a but too.

[DIYedInTheWool]

Looks great. Did you decide which orientation you're going to build on?

[pippin88]

Attachment 255754

I'm going for this orientation. Means two epoxy pours (table area and beams) and waste some epoxy on bridges between the beams, but uprights are 5cm shorter which means stiffer.

[pippin88]

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.

First attachment:
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.

Second attachment:
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.

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


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.

[pippin88]

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.
(CAD updated.jpg)

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:

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

(Router on Table.jpg)
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.

(Toppled.jpg)
A controlled topple / slide forwards on to the saw horses.

(Cart in position.jpg)
Moved the table back and rolled the cart in to position.

(Controlled descent.jpg)
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).

(Up.jpg)
Tip it upright fully.

(and away.jpg)
And we are rolling.

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

[pippin88]

Work is progressing. I had a set back while milling Z axis parts: the brass motor gear in my mill shredded itself leaving only flakes and dust where the teeth had been. I'd started a belt drive conversion ages ago but abandoned it as my lathe blew a gear and had some other issues. So after much struggling and kludge fixes on the lathe I now have the mill belt drive done.

In the meantime I've got the main router epoxy pour done. It went ok and looks good now. I had a couple of stuff ups:
1. I tried to cover it with a suspended cloth to keep dust and chips out - the cloth dumped a load of fibres all over the epoxy... It didn't do that when I used it for the gantry epoxy cover.
2. I managed to droop the cloth on to the epoxy. It'd been curing for a few hours and so was starting to gel and a few humps were created by the contact, but still seemed to start to level / smooth.
3. Watch the heat - I'm using a pocket butane blow touch to get rid of bubbles. It also temporarily makes the epoxy flow easier (viscosity falls with rising temperature). However I went a bit overboard trying to fix the spots the cloth had touched and managed to cook a few small areas of epoxy. This meant I had to fish these cured discs / thin bits of epoxy out and the epoxy had to self level again.
4. I switched to fast epoxy for the dam sealing step on this last pour. This works much better, but pay attention to the pot time. I was a bit slow and had a pot start smoking then suddenly go off. Had to drop the cup on the concrete and the disposable cup melted.
Despite those problems it looks like it's gone well overall.

Tips for self leveling epoxy
You need the right epoxy - slow, low viscosity for self levelling. I used West System 105 + 209 hardener. Certainly not cheap, but others have used with good results.
Get the object as level as possible as you'll need less epoxy
Clean the object then let it dry
There are two main stages:
A) Building a dam and sealing it
B) Pouring the main epoxy

A) The dam
You need something the epoxy doesn't stick too. It won't stick to the non sticky side of most tapes. It will stick to metal and wood.
I tried gaffer tape, duct tape, and blue painters masking tape for various parts.
Definitely use the blue tape (also called 14 day painters tape).
Advantages:
1. It's stiff and therefore forms a nice straight dam
2. It's low tack so doesn't pull your paint off, and it's possible to reposition if you don't apply it perfectly
Gaffer tape works but is too sticky and pulls off paint, and is also hard to apply as well as the blue tape.
Duct tape stretches and curls, so doesn't give a nice flat edge.
I found a single layer of blue tape carefully applied worked well, with particular attention to the corners.

You must then seal the dam. This is done by applying a small amount of epoxy around the join between the dam and the object. You only want a small amount - this is done by applying with a spoon or knife, not pouring. If you stick to a small amount it will bridge small gaps and hold in place with surface tension - if you pour too much gravity will overcome this and it will flow through the gaps. Use fast curing epoxy for this. I used West System 105+205 hardener. The fast curing epoxy tends to be more viscous (an advantage at this stage) and works quickly to seal gaps. I used very slow epoxy for my first couple of dam sealing and it was a pain - it's runnier and it has time to all flow out before it cures.
Be ready for leaks. Tape doesn't really stick where the epoxy is running, but if you whack enough on, the tape sticking to either side of the area will be enough to hold it and you can create an effective barrier. Blutack works also and is of course mouldable, but try to avoid it. It won't adhere where the epoxy already is, but does get incorporated in to the epoxy edge. However I did use it effectively to physically cover small leaks that would have been unfixable otherwise. You'll need big lumps of it.
Now you have to wait till the sealing epoxy is solid enough. It doesn't have to be fully cured / full strength. If you used fast curing epoxy (seriously don't even consider using slow) you can proceed to the main pour a couple of hours later.

The main pour
As mentioned above, you need slow curing low viscosity epoxy.
Mixing in a large shallow dish gives you more pot time.
Mix thoroughly but avoid vigorous mixing as you want to avoid introducing bubbles.
I mixed in batches based on my mixing container size.
When each batch is mixed, just pour it on. Spread out where you pour fairly evenly so the epoxy doesn't have to travel as far.

Be aware that surface tension is a significant factor and there is a minimum thickness to self level. This will vary with the epoxy, and I'm not sure what it is, but I guess and good 2mm at least. You won't get self levelling with 0.5mm thickness. I used to spoon to spread the epoxy around a bit also.
Fingers crossed you have no leaks.
Now you need to get rid of bubbles. This is done with heat, either a small blow torch / gas soldering iron, or a heat gun. Do not use a hair dryer as the air flow is too much and will blow dust in. I opted for a small blow torch as I can use it for other things. Wait a little for the bubbles to rise then gently waft the torch over the surface. Don't stay in one area too long - you'll cook the epoxy and I'm sure burning epoxy fumes aren't good you for either. You'll probably need a few passes, it's surprising how much bubbles you'll have. Bigger bubbles cause significant surface irregularities. Often you'll only see that bubbles are present if you use look at the epoxy with a bright light, such that the epoxy is a mirror and you are looking at the light bulb on the surface of the epoxy.

I left each pour a full week to achieve good strength before disturbing.

Heating the epoxy components reduces viscosity. This is done by putting the bottles in a bucket of warm water. However, this reduces pot life / speeds up curing. Apparently heating the object to be poured on still gives the benefit of better flow but doesn't speed up curing, which would be ideal.

Once your epoxy is cured you'll need to remove the fairly large meniscus. Be careful, the edges will be sharp. My hands are covered in cuts from my clean up.
Use a file to break the edges then take down the meniscus. Epoxy files easily and doesn't clog a file like it will sand paper.

[Seelesturm]

Thanks for posting your build. It has helped me understand the epoxy leveling process quite a bit. Im using your thread, as well as some old builds, as a bit of a motivator for my next build.

Did you end up creating a bridge between the two rail surfaces on the table assembly, or did you pour each of them separately? Did it work very well for you?

I have never used epoxy like this before. My two rail surfaces will be around 30" / 800mm apart. Ive thought about bridging the two rails together, but am unsure of how wide the bridge needs to be to ensure that it actually levels out accross the two planes.

Thanks for posting your build, it looks great so far!