El Beast - Initial design phase, comments and critique welcomed!

**Zeeflyboy** · 03-11-2018

Hah thanks, hopefully it's art that works well too!

Wasn't entirely happy with my designs for the gantry and yesterday I sat down and had a bit of a play around with some ideas. This is where I've got to so far, and I'm pretty happy with the concept... just some finer details to nail down like grease port access.

The basic idea - main plate that mounts to the 200x40mm extrusion has been bumped up to 25mm while the rear plate will now just be a cover so overall material amount is similar. Staying with the original direct drive but with the extra width of the newer gantry this can be accommodated inside the frame by a cutout in the gantry arm and a small cover. The extrusion will have a couple of channels milled in to give clearance for a 30mm polypropylene webbing belt which will move with the sliding plate.

Looks complicated, but actually is fairly straight forward... think it'll be fun to have a play with.

So the overall gantry section

Rear extrusion removed and one belt gone so you can see the roller/guide mechanism

Top sealing strip removed

Belt/clasp detail

**jarjar** · 03-11-2018

I like your idea for protecting the motion bits. I may steal it for my own build :)

The gantry looks rather thin to me... And thus torsionally weak. I would go with a Misumi GFS8-100200, at a minimum.

**Voicecoil** · 03-11-2018

+1 - you just beat me to it Jarjar as I was calculating!
I've just done the sums on a piece of 25 x 200 plate and it's something like 17x weaker torsionally than a piece of the 200x100x5 box I'm planning on using for mine: adding the bit of extrusion on the back will help depending on how comprehensively they're bolted together, but it's unlikely to achieve the same rigidity as a decent box section. OK 100mm deep might be a bit much, but there's a 200 x 80 x 6 that's nearly as stiff. And with a box you could maybe run the returns of the slot covering strips back down inside it - at least that's what I'm planning

.

**Zeeflyboy** · 03-11-2018

Originally Posted by Voicecoil

there's a 200 x 80 x 6 that's nearly as stiff.

At misumi? I can't seem to find a 200x80 anywhere.

**Voicecoil** · 03-11-2018

Originally Posted by Zeeflyboy

At misumi? I can't seem to find a 200x80 anywhere.

It's just a normal box section extrusion - these are my local stockists:

https://www.simmal.com/product/alumi...tangular-tube/

**Voicecoil** · 03-11-2018

If you want to stick with profiles, Item do a 80x200 that's not bad as far as profiles go:

http://catalog.item-central.ca/en/pr...-8-200x80.html

**Zeeflyboy** · 03-11-2018

problem is finding somewhere to buy it in UK.

Cheers guys, I'll have a think - 80mm would be easier to work into the design than 100mm but 100mm is easily available at misumi where I need to buy some profile anyway.

**Zeeflyboy** · 03-11-2018

I believe I could make the 80mm work, although it would need new plate ordered for the side arms as the stock I have isn't big enough). Problem will be finding somewhere to buy it - have sent an enquiry to ITEM and to another place, will see what comes back. In the mean time I can continue to work on the design as it only really changes the side arms... will run both ideas and maybe look into simulations to get an idea of differences if I can wrap my head around it sufficiently well to simulate a fairly complex construction.

Oh and just printed out a shield belt clasp to see how it would come out - seems to be good, can pull on both ends pretty hard and no give

**Voicecoil** · 03-11-2018

Originally Posted by Zeeflyboy

problem is finding somewhere to buy it in UK.

Talk to Pamela at MBS <[email protected].> they're the UK agents for Item stuff, seem to be able to get most stuff within a week or so. Not cheap, but then quality rarely is I guess, and they seem to be a good source of heavyweight profiles.

BTW, how does your tramming plate work please? is the back of it machined to a very gentle radius so you can tilt it?

**Zeeflyboy** · 03-11-2018

Originally Posted by jarjar

I like your idea for protecting the motion bits. I may steal it for my own build :)

The gantry looks rather thin to me... And thus torsionally weak. I would go with a Misumi GFS8-100200, at a minimum.

Interesting. Just to be clear the part of the gantry that is actually doing the work is 65 x 200 mm made up of a heavy 40mm extrusion and a 25mm tooling plate, not just the 25mm tooling plate on it's own. The span is 620mm... it also has 6mm plate top and bottom which will be screwed down to the extrusion and the tooling plate. Given the relatively short span I don't think it should have much flex?

I could possibly re-work the design to use a 200x100 extrusion, but I think it would almost certainly require me to order new 25mm plates for the side arms as I'd need to take it further back at the top to accommodate some of the width. It is possible though as I need to order new extrusion anyway so I will have a play and see what I can come up with.