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

**Zeeflyboy** · 26-03-2017

I thought about that, and I may yet do so... The problem I'm thinking is that it really helps me out if these are perfectly matched length wise. Given that I'm sure they set the cutting length and then chopped one after the other, when done as a pair they should be pretty much spot on. If they send me a single one to replace the dinged piece then there is no guarantee that it will be as closely matched and will be subject to their cutting tolerance instead (which they don't actually seem to specify, other than allowing you to dictate product length in 0.5mm increments).

So given that consideration, along with the fact that the corner will be totally hidden once constructed, I'm leaning towards just sticking with it rather than risk extra alignment headaches by slightly mismatched lengths.

But anyway, to answer your question the profiles themselves are pre-milled pieces from misumi. The cross pieces are HFSP8-5050 (50mm square profile, milled on 2 sides - so actually 49x50mm) while the larger ones are the bulkier high rigidity GFSP8-10050 (100mm x 50mm, milled on the 100mm sides, so true dimensions are 100x49mm). Misumi have a variety of milled profiles so you can probably find one that suits what you need - the issue is actually ordering it if you don't work for/own an appropriate company as they won't sell to normal plebs like us.

**1Jumper10** · 26-03-2017

Looks very nice. I've heard good things about Misumi extrusions and they were one of the sources I had considered using in the past but I've never ordered anything from them. Thanks for the pics. They confirm my perception of Misumi's quality. Given the quality of the extrusion, do you think you really need the Thor Labs corner brackets? Looking forward to your build...

**Zeeflyboy** · 26-03-2017

There is probably an argument to be made that I could live without them...

Maybe I'll go with just a single pair at the front and see how it comes out... easy enough to add a second pair at the back if required.

On a related tangent I've been working on a custom tool drawer insert for my CNC bench... still haven't placed all tools yet as I haven't fully decided what I want to put in... also need to make the handle in the front.

**Zeeflyboy** · 31-03-2017

So as promised, something more scientific....

I used my touch probe to measure the length of the cross braces. Fairly impressive cutting tolerance really I suppose, the nominal length was 344mm and the longest was 344.34mm while the shortest was 344.28mm so they are within 0.06mm of each other. Would have been even more impressed if they were all 0.3mm shorter

So my options are to use some shim material to make them all up to an effective 344.34mm or I can try to nip them all down to 344mm on the CNC... Shimming is probably the least risk route.

**Zeeflyboy** · 06-04-2017

Got home today to find FedEx had left me a nice treat:

My linear motion stuff arrived, and initial inspections it all arrived intact. HG25 rails and carriages could probably be used for seal clubbing if one were so inclined... didn't realise quite how beasty those are.

Quality of the TBI ballscrews looks to be fantastic - finish is excellent, as is the end machining and they are as straight as an arrow with absolutely no discernible slop or play on the ballnut. I intend to do some tests with the glass scales just to see what that tells me but from a visual inspection stand point they seem top-dolla!

some linear motion porn (NSFW?)

Had a bit of an order snafu with Thorlabs - got an order receipt and they reserved funds on my bank account but the order didn't get processed. I have spoken to them and re-ordered so those should be arriving shortly. Other than that I'm just waiting on an order from motedis for various extrusion related fixings and then I should have most of what I need for the bottom frame build.

**Neale** · 06-04-2017

Out of curiosity, where did the linear motion bits come from?

**Zeeflyboy** · 06-04-2017

Topper on aliexpress... I was dealing with a guy that goes by the name of John (I would assume a western friendly name!) - very helpful chap. Just emailed him asking for a quote for all parts with details of what I needed and then they can create a special order for you on aliexpress so you still get the buyer protection afforded by them.

I was one HD16 short (can't really complain since they threw those in for free) and I've sent an email to enquire about that so we'll see what they say. They do both TBI, HIWIN and they do their own factory Chinese made stuff too which would work out quite a bit cheaper. For this machine I went with the HIWIN rails and C3 TBI screws, for my other project I went with some of their own factory manufactured ground screws and nuts which were significantly less than the TBI equivalent (C5 ground 1204 screws are very expensive it seems!). On first impressions those factory own screws look well made too, and while they don't have any discernible play on the nut they aren't quite as smooth to spin by hand as the 16mm TBI ones for El Beast.

Was very happy to see the end machining has been done to a very high standard - bearings are a snug fit and the machining is concentric. All the other parts like rails, carriages, MBA-12C mounts, FK and FF bearing sets seem high quality - So far so good.

As mentioned I want to check the screws against the glass scales just to check lead error and consistency more out of interest than anything else, but having had a good look at them I would be surprised if they were anything other than excellent.