Smartrapcore alu "250xl" build

So I decided to enlarge my Smartrapcore Alu to a larger bed. I didn't want to go all the way to the 300xl, as I wanted to be able to increase one dimension but via the easiest and least costly route possible.

So I decided to just enlarge the frame in the x dimension by 10cm. All that is required to do this is:
-4x2020 extrusions 500mm
-2x8mm smooth rods 380mm
-Mk2b heated bed 200x300mm
-glass 200x300x3mm

I also wanted to upgrade all my printed parts to ABS (for later use with a heated enclosure). Relocate my power supplies to below the machine, and change my pulleys for flanged bearings. In order to change the pulleys I used modified y-slides with cutaways to prevent the belts fouling. [www.thingiverse.com]





So far I have not yet changed the z axis bed support and installed the new larger bed. I wanted to test the machine briefly with this new larger x axis to ensure the 8mm rods are performing very well. There is no noticeable sag in the middle, at this stage moving up to larger rods, or linear slides doesn't seem necessary.

Next step is to make a plywood base for the z -axis and install the new bed. I do not yet know how well this axis will cope with 50% more bed width, it might need supports on the left and right sides. If so I'll use rods/bearings attached to the sides of the z axis carriage. I have the two 8mm rods I replaced on the gantry to use.

Edited 1 time(s). Last edit at 05/09/2016 03:52PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Shit homie, you da best
I don't know how black people speak, but good job, i was just thinking "maybe i should've gone with the xl300" and bam, here it is, doubt gone.

Also, how's the titan doing ? Did you acquire it ?

Thanks, although its a reasonably simple upgrade - the big question was whether the 8mm rods were up to the job. I think the ones I'm using now are better quality rods (got them from wedo3dprinting on ebay) or just mounted better - they are much stiffer than the similar length rods in my i3 (which bend like a wet noodle).

It was nice to rebuild the frame as I am sure the first time I built it in a bit of a hurry and it wasn't quite as square or tight as it is now.

I got the titan, but fitted it to my kossel mini, where it is performing with the small 20mm nema 17 motor brilliantly. I am quite tempted to get another and see how well it works on the new SCALU "250xl" but the flex3drive is just too good. So that's a project for you or someone else I think.

I am going to get some plywood to make the z-axis base for the new 20x30cm bed, I found a really good website [www.woodbin.com] which can determine how thin a piece I can get away with without it bending. Once I've tried it with plywood, I'll lay out a version for laser cutting and see if I can get a nice aluminium bed support made instead.

Edited 2 time(s). Last edit at 05/09/2016 03:50PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Z Axis carriage 9mm plywood. Drilled to save weight. Given a coat of silver paint.
Is actually quite rigid. So at this stage I am not planning to add any more support/guidance on this axis. But will review this once I'm printing on the new larger bed.


One other issue to iron out, slight rubbing of the higher belt on one of the washers above the bearing/pulley.
Also the path of the belts to/from the x carriage is slightly angled. I might try Realthor's smartrapcore compatible x carriage with double sided belt tensioning.

Edited 1 time(s). Last edit at 05/10/2016 05:14AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Mh ... well, the xl300 has 8mm rods, with direct extrusion, so if they don't bend there, where would they ?
Also, my alu is late, so they made me a discount offer, if i want i can have the xl300 alu kit by adding only 80 €, should i go for it in your opinion ? The bed size and direct extrusion are really tempting .....

Yes I think I would for that money.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

yeah right ?
Worst case scenario i'll send it back, best case scenario, it prints like a dream and i can print myself a girlfriend.
Or at list a pair of tits.
And i won't have to upgrade the frame or the bed later, just eventually the plastic parts to nylon and the rods to 12 mm ones

Well the build is finished. Sorted out the rubbing bearing by lowering one of the rear pulleys. Got the bed attached and working, takes a little longer to heat up but it is 50% bigger. Not quite perfectly level but close enough. Printed some cubes, look okay need to tweak the bed level a bit.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Found that the reprap.me 200x300mm mk2b pcb heater would only draw 4amps @ 24v. Meaning that it was taking a long time to heat up and wasn't getting up to 110 degC for ABS. So I connected the 24v to the 12v connectors, which now runs my 250w 24v PSU at 12amps which is maxing it out, its not too hot to touch (so below 60 deg C), the bed heats up very quickly now just 4 minutes to 110 degC - I might add a fan on the PSU for peace of mind. The 24v supply is to the heatbed only, via a mechanical fused relay and using bang bang control.

The other issue was that I hoped to use an SMD thermistor with this heatbed as it has the solder pads for one. I tried a NTC, 0603, 100K, NTCS0603E3104FXT thermistor but its profile did not match any of the thermistor tables in Marlin. I did start the process of calibrating it and making a new thermistor table, but got bored doing this and decided to just attach a regular thermistor to the underneath of bed instead.

Edited 1 time(s). Last edit at 05/13/2016 10:03AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Did you do any other research on those rods ? I'm afraid they might bend in my xl300
Also, as always, good job man

Well I did use some deflection calculators but its difficult to assess the level of rigidity in the support for the rods, get a total mass for the print head etc... I calculated 0.15mm sag in the centre but I wouldn't agree with that in practice they seem very rigid. Changing to 10mm/12mm rods would be fairly easy, modified y slides, modified x carriage but I don't think I'll need it.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

One issue I still have is the bed level is a bit off at one corner I don't think it's bent glass, it's the front right y smooth rod holder which is a bit vague, so I wonder if the y axis is slightly twisted. I will redesign this part as the original is not very positive, unlike the left side front y smooth rod holder which is much better designed.

Edited 1 time(s). Last edit at 05/14/2016 05:16AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

yeah, that's also what i thought, i read some people talk about rods bending, but that's assuming the plastics won't bend before the rods, and realistically speaking, they will ...

Well the rods sag in the middle as it's the rod that is in the middle. On my i3 there is a "hill" in the middle of the bed which is the rods and the plastic supports sagging. I haven't noticed it on the smartrapcore yet the rods aren't that long even on the enlarged version and they are well supported.

And the print head is much lighter.

Edited 1 time(s). Last edit at 05/15/2016 09:04AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

You have really big i3 ?

No but its a common fault the rods are quite long and I suspect given the cheap build quality of the printer probably poor quality metal. If you level the bed at the four corners then check the level at bed centre it will be slightly lower I. E. the nozzle closer to the bed,this has to be the x axis sagging.

Edited 1 time(s). Last edit at 05/15/2016 09:28AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

So its finally finished, enclosure completed with addition of acrylic top cover.

(click to view this in portrait - the wiring still a bit of a mess)

The chamber is managing 67 deg C without any additional heating. Which I am very happy about, all the electronics and motors are outside the chamber.
Now to print some really big stuff in ABS.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions