1st Build, Steel, Epoxy 24"x24" for Wood

Initially posted here:
http://www.mycncuk.com/threads/11310...-advice-please

Decided I'm at the point where a build log is in order. Still looking at wood only, but would like to toss 3D carving into the mix. Table is built from 2"x2" square tube steel, 1/8" thick. I will be adding steel strips for more thread engagement where needed.

Ordered linear rails and ballscrews for Y-axis (X-axis?, still haven't figured that out) from Fred at BST. Trying the 20mm Chinese ones. Saving the 35mm NSK surplus ones I ordered before for a later project.

I know I'll get bruised up a bit for this, but I am somewhat "designing as I go". Getting handier with F360 though, so I'll finalize a gantry design before going that far. Here's what I have for now:

Attachment 22993

Ordering epoxy to provide coplanar place for mounting rails. Gantry thoughts are something similar to what Joe Harris is building. Looking at 1.5kW water-cooled spindle with ER16, 4 bearings, real HY VFD.

Questions:
1. More bracing needed? I am thinking of angled supports for top rails.
2. Any experience with the Chinese rails from BST?
3. What should I be thinking about now to avoid headaches later?

Thank!
Wallace

Hi Wallace,

I would brace the underframe a bit with either some vertical pieces mid span, or diagonal across each side.

1.5kW spindles often come with ER11 collet (max 7 mm), although some are ER16 (max 10 mm). But my advice is go for 2.2 kW and ER20 (max 13 mm) as it will give you more options. The extra power will help with the torque at lower speeds. They are all 80mm diameter for the main body so shouldn't effect your design.

If the gantry will ride on those side members is there enough clearance in Z movement to the bed? Check they are going to be high enough.

If I did a couple vertical braces mid-span, you think I'd have to then add legs in the middle too?

You are dead right on the collets. I have an ER32 shank for my Bridgeport and was thinking ER16 was ER32 (powers of 2...damn computer geek :). I'll look at 2.2kW spindles.

Not sure I understand the Z clearance question... I'm planning on a beam gantry (if I have my terms correct), so wouldn't taller sides give me the clearance needed? Within reason of course.

Thanks,
Wallace

Taller sides will get you there! And from what I understand that's perfectly alright for wood routing.
If you plan on aluminium then raising the frame sides are a more rigid solution then taller side plates for the gantry.

Glad to see that you are progressing :D

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Also the braces that routercnc mentioned are most likely diagonal braces.
If you brace diagonally in as many directions as possible it will reduce flex in the entire machine when you are routing full speed later.

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Added these:
Attachment 23015

Epoxy should be here this week...

That's good in front to back direction.
Side to side could use some diagonal lovin aswell ;)

What epoxy have you ordered?

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Yeah, you're probably right. Sigh, I never thought I'd get tired of welding!

I may get some grief, but I ordered Totalboat 5:1 epoxy. Supposed to be equivalent of West at about half the price. Actually, it wasn't so much that it was cheaper - they had a nice kit on Amazon with resin, slow hardener, metered pumps for each, and mixing containers. Specs have viscosity with slow hardener at 700 Cps, which is actually lower than West's 1000 Cps. So should flow as well or better.

Thanks,
Wallace

Quote:

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Originally Posted by wallyblackburn

I may get some grief, but I ordered Totalboat 5:1 epoxy. Supposed to be equivalent of West at about half the price. Actually, it wasn't so much that it was cheaper - they had a nice kit on Amazon with resin, slow hardener, metered pumps for each, and mixing containers. Specs have viscosity with slow hardener at 700 Cps, which is actually lower than West's 1000 Cps. So should flow as well or better.

Thanks,
Wallace

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Being a skin-flint I'm very curious how successful different cheaper epoxies are at self-levelling, so please report back when done.

Had a look on the web and wonder whether you've gone for just the Slow-Hardener or the Extra-Slow-Epoxy-Hardener which seems to me to be closer to the West system that the successful pours on this forum have used?

5:1 Slow Hardener ~ http://www.totalboat.com/product/51-slow-hardener/
• Excellent thin-film characteristics provide smooth flow-out and self-levelling ideal for coating and laminating
• Pot life @ 75°F: 20 minutes
• Set time @ 75°F (thin film): 10 hours
• Cure time @ 75°F (thin film): 1-4 days

Tropical Extra Slow Epoxy Hardener ~ http://www.totalboat.com/product/tropical-hardener/
• Excellent thin-film characteristics provide smooth flow-out and self-levelling ideal for coating and laminating
• Pot life @75°F: 46 minutes
• Set time at @75°F: 20-24 hours
• Cure time at @75°F: 4-7 days

I used reactive resins slow kit. Don't remember the exact specs for it but it worked real good :)
It was about half the price of West 105/209 and it shipped to Sweden without hassle!

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Quote:

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Originally Posted by AndyGuid

Being a skin-flint I'm very curious how successful different cheaper epoxies are at self-levelling, so please report back when done.

Had a look on the web and wonder whether you've gone for just the Slow-Hardener or the Extra-Slow-Epoxy-Hardener which seems to me to be closer to the West system that the successful pours on this forum have used?

5:1 Slow Hardener ~ http://www.totalboat.com/product/51-slow-hardener/
• Excellent thin-film characteristics provide smooth flow-out and self-levelling ideal for coating and laminating
• Pot life @ 75°F: 20 minutes
• Set time @ 75°F (thin film): 10 hours
• Cure time @ 75°F (thin film): 1-4 days

Tropical Extra Slow Epoxy Hardener ~ http://www.totalboat.com/product/tropical-hardener/
• Excellent thin-film characteristics provide smooth flow-out and self-levelling ideal for coating and laminating
• Pot life @75°F: 46 minutes
• Set time at @75°F: 20-24 hours
• Cure time at @75°F: 4-7 days

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I went with just the slow - not extra-slow. It will likely be in the 65F temp range here when I pour...

Well, I have it about ready to pour epoxy:

Attachment 23021Attachment 23022

Can't figure out why my pics are upside down now...

Brushed a thin coat on to seal joints, seams, etc:

Attachment 23029
Attachment 23030

Still trying to get pics right-side-up. I think it has something to do with iOS 11

Read over more epoxy-related posts before pouring and came across the one by Boyan Sylvaski discussing shrinkage of centered bridge causing distortion in the middles of the rails! Well, I wasn't tearing it down and starting over. So, I did the pour, gave it time to flow out, and then blocked the bridge entrances with razor blades:

Attachment 23037 Attachment 23038

Used a heat gun multiple times to get rid of bubbles. I was surprised at how well that worked. You could see the bubbles pop and disappear as you waved the heat gun over. Top looks like glass at this point.

Wallace

Pulled forms off today. Not sure if this was because I used the Totalboat epoxy, but I was surprised at the size of the meniscus. I have one side pretty much cleaned up, but I'm guessing I had to file in maybe 5mm from the edge to get rid of it. Does this sound like what most of you see? Nothing to base this on, but I expected it to be a narrow and steep meniscus. I'll try to get a pic of the other side before cleanup.

Linear rails supposed to arrive from China this Friday...

I've not done epoxy before but your query may be answered in this excellent epoxy thread :
http://www.mycncuk.com/threads/8197-...-for-levelling

IIRC others have suggested pouring epoxy 40mm wide for 20mm rails to allow for a miniscus of about 5mm and then some.

Wow.. fast progress! I had my moat on for 8-10 days for guaranteed cure..
But you didn't have the super slow stuff?

I used reactive resins and had about 4-5mm meniscus.

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Or maybe I just rushed it :(

It seems super hard though. I used the slow - not extra slow. Sounds like the meniscus on mine was about right then. Still amazes me how this works. I could not get the frame level in all directions due to an apparent twist. But no matter which way I put this level, all I see is:

Attachment 23082

Granted, that is just a (high quality) carpenter's level, but still pretty cool.

Thanks,
Wally

Yeah I know :D
I was amazed with the glassmooth level surface..
Awsome stuff for DIY applications.
I was a bit stupid as I built my moat out of masonite and the epoxy merged with it. Proper hell to clean :)
Did the tape you used come of easy?

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No, it was also proper hell also! I'll use packing tape backwards next time as Clive and others suggest...

Quote:

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Originally Posted by wallyblackburn

No, it was also proper hell also! I'll use packing tape backwards next time as Clive and others suggest...

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I was not aware of this requirement.

Never had thought of this simple solution myself.

I will use cheap packing tape for my pour.


thx guys.



Grtz Bert.




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Got the rails and ballscrews for Y-Axis from Fred at BST. Got epoxy cleaned up and mounted first rail. Tried to rough-align second rail using some equal length bars between them and could not get them lined up. Took one off and put it on my surface plate. Nice and flat on top and bottom, but crooked as a politician in the horizontal plane. Getting 12 thou out towards ends.

Thinking this is to be expected when you pay $282US for 2 rails, 4 trucks, and 2 ballscrew assemblies. Anyway, guessing some others have dealt with this? What did you do?

I'm thinking of tightening down in middle, and then working my way out trying to pull the rail to a straightedge and cinch it down. Maybe make a saddle kind of jig that will give me a screw to adjust the rail before tightening it down. Sounds dodgy.

Thoughts?
Wallace

Hi Wally
Nice work with the pour, i explained this a while back but have not been able to find the thread it was on, but you are correct, fix the centre of the rail first then work your way outwards setting your rail to your straight edge, clamping the rail, drilling and tapping and then securing as you go.
Regards
Mike

Allow me to retract at least most of my last entry and apologize to our Asian friends. Oh...and admit to being a dope that goes off half-cocked...

I was looking at the edge along the base near the mounting surface - which is not really a reference surface, I don't believe. In checking the side of the rail where the balls ride, I get less than a thou over any 6-8 inches. At this point, I am just going to start on the gantry mounting and check it at different points as I go.

Regards,
Wallace

I think you will find some marking on the rail depicting the master/reference edge, once you have that set to your straight edge it would probably be better to use your gantry to align the second rail.
Mike

Quote:

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Originally Posted by wallyblackburn

At this point, I am just going to start on the gantry mounting and check it at different points as I go.

Regards,
Wallace

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This is how I did it.
First rail as straight as possible then I mounted the gantry and slid it back and forwards as I was drilling.
Then I took it off and tapped all holes.
Then remounted for tightening the screws and worked as close to the gantry as possible :)

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Quote:

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Originally Posted by Nr1madman

This is how I did it.
First rail as straight as possible then I mounted the gantry and slid it back and forwards as I was drilling.
Then I took it off and tapped all holes.
Then remounted for tightening the screws and worked as close to the gantry as possible :)

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I have a feeling that that is also suggested in the Hiwin manual. Certainly worked for me!

Quote:

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Originally Posted by Neale

I have a feeling that that is also suggested in the Hiwin manual. Certainly worked for me!

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Oh! Haven't read that one..
I have noulei cheapo bearings (no manual) ;)
I read the mycncuk diy manual. It's quite a read but lots of good pointers.
And the best part.. it got pictures! :D


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I did read the manual but all the warnings about how accurate you need the mountings to be worried me so much that I closed the manual and just carried on anyway!

That sounds sane! Sometimes you just have to check what works hands on..

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Wow! I was thinking it had been over a year since I last posted - but then realized the dates are DD-MM-YYYY and not MM-DD-YYYY! Anyway, got sidetracked somewhat with a surface grinder I picked up at auction. That, along with a surface plate and measuring tools pulled me into the world of tenths. A scary, but fun place. I like This Old Tony's description of his surface plate: Where dreams go to die... Anyway, gotten back to the router recently:

Attachment 23704 Attachment 23705 Attachment 23706 Attachment 23707Attachment 23708 Attachment 23709 Attachment 23710

Now, I know it isn't pretty. Please keep in mind my goals for this are to learn and gain experience. I would like it to cut wood at a reasonable (woodworking) level of accuracy at some decent speed, but I'm mostly having fun and building skills and knowledge to make a better one after this - if I decide I want to.

I just ordered rails and ballscrews that are 50mm longer than the ones in the pics. I intend to move the existing ones to the gantry and put the new ones in their place. This should give me bit more travel and get the ends out where I can get pulleys on them. I am thinking of driving the two Y-axis screws with a single NEMA 34 and timing belt arrangement. The X- and Z-axes will be NEMA 23.

Can I get opinions on this kit: https://www.ebay.com/itm/FEEE-Ship-3....c100005.m1851

I'm leaning towards a Centroid Acorn controller.

So, given the above, I'd love some input, guidance, even criticism.

Thanks,
Wallace

Quote:

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Originally Posted by wallyblackburn

Wow! I was thinking it had been over a year since I last posted - but then realized the dates are DD-MM-YYYY and not MM-DD-YYYY! Anyway, got sidetracked somewhat with a surface grinder I picked up at auction. That, along with a surface plate and measuring tools pulled me into the world of tenths. A scary, but fun place. I like This Old Tony's description of his surface plate: Where dreams go to die... Anyway, gotten back to the router recently:

Attachment 23704 Attachment 23705 Attachment 23706 Attachment 23707Attachment 23708 Attachment 23709 Attachment 23710

Now, I know it isn't pretty. Please keep in mind my goals for this are to learn and gain experience. I would like it to cut wood at a reasonable (woodworking) level of accuracy at some decent speed, but I'm mostly having fun and building skills and knowledge to make a better one after this - if I decide I want to.

I just ordered rails and ballscrews that are 50mm longer than the ones in the pics. I intend to move the existing ones to the gantry and put the new ones in their place. This should give me bit more travel and get the ends out where I can get pulleys on them. I am thinking of driving the two Y-axis screws with a single NEMA 34 and timing belt arrangement. The X- and Z-axes will be NEMA 23.

Can I get opinions on this kit: https://www.ebay.com/itm/FEEE-Ship-3....c100005.m1851

I'm leaning towards a Centroid Acorn controller.

So, given the above, I'd love some input, guidance, even criticism.

Thanks,
Wallace

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I don't care what you say she's a looker ;)

nice work, personally I'd go with 2 nema 23 for the Y and get AM882's or equiv but I'm scared of belts lol.

Well done ;)

I looked at the kit you linked to.
Have no clue about specs for the nema34 so it might be good but the nema23 is really high inductance and will perform poorly.. the ones from zapp or cnc4you are much better!

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Quote:

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Originally Posted by Nr1madman

Well done ;)

I looked at the kit you linked to.
Have no clue about specs for the nema34 so it might be good but the nema23 is really high inductance and will perform poorly.. the ones from zapp or cnc4you are much better!

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Thanks for the info. I quickly get overwhelmed when I start looking at motors and drivers. Especially if you throw closed loop steppers and servos in the mix! If I do go with open loop steppers, what are some guidelines for max inductance for nema23 and 34 motors?

Regards,
Wallace

Quote:

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Originally Posted by wallyblackburn

Thanks for the info. I quickly get overwhelmed when I start looking at motors and drivers. Especially if you throw closed loop steppers and servos in the mix! If I do go with open loop steppers, what are some guidelines for max inductance for nema23 and 34 motors?

Regards,
Wallace

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For nema23 and 3-4nm strength then no more than 4mH. Less is better!

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Quote:

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Originally Posted by Desertboy

I don't care what you say she's a looker ;)

nice work, personally I'd go with 2 nema 23 for the Y and get AM882's or equiv but I'm scared of belts lol.

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Lol - and I'm scared of slaving axes! It is sounding like Centroid will have separately homed, slaved axes in an upcoming release, but I'd like to keep that 4th axis available.

Thanks,
Wallace

Quote:

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Can I get opinions on this kit: https://www.ebay.com/itm/FEEE-Ship-3....c100005.m1851

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Kits are never a good idea as the are never matched. The motors are too high in inductance, you would be better off with higher voltage drives and power supplies. The machine look bigger than 24"x24". It would be nice if you could rotate the pics.

Quote:

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Originally Posted by Clive S

Kits are never a good idea as the are never matched. The motors are too high in inductance, you would be better off with higher voltage drives and power supplies. The machine look bigger than 24"x24". It would be nice if you could rotate the pics.

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I'll keep that in mind. I was thinking it might be cheaper - but if it's wrong... I still don't understand why my pics get rotated 90 degrees when uploading. I guess I'll try rotating them 90 the other way *before* I upload.

Thanks,
Wallace

Given you're on the other side of the pond, I would of thought Gecko drives would be a reasonable first choice, as you won't have the issue of import tax and VAT to worry about, which makes them poor value here.
However Leadshine AM/EM drives might be worth considering for the sole benefit of having stall detection, which I'd recommend for any twin screw axis (should a single screw axis stall, it's not normally a major problem machine wise, but on a twin screw axis, you risk twisting the gantry if one screw stalls and the other keeps going - even with stall detection you'll likely still get some twisting, but all motion should stop far quicker minimising or eliminating damage).

Gecko used to also sell some pretty low inductance Nema23 motors, but I see they've stopped selling them.
I'd have a search of the more American based forums to see where people are sourcing motors.

Hmm keling is us based I think.. they have good motors! :)

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