My Momus build

[TeslaFreakshow]

Hi Everyone,

This is my second time typing this so I'm going to make it shorter. Accidentally hit the back button.

I bought the Momus design on Ebay a week or two ago and started the build this week. The seller directed me here. Ive been following a few builds too.

I decided to make my frame from steel tubing instead because I had trouble finding the 3/8 wood and didn't want to substitute. I figured id overlook something and it would end up not working. I figured the tubing would be easier since its more simple. My welder has been gathering dust for around 6 months anyway.

My steel frame is just about finished it just needs the wood base im going to add and epoxy pour. I extended the y axis about a foot but left everything else the same. The height is exactly the same as well including the height difference the two rails have from each other.

[IMG][/IMG]

-Tom

[momus_cnc]

Hi Tom,

Wow, that is quick progress. That's a very attractive frame. Nice build quality. What is your plan is to mount the stepper motor?

It seems like building welded steel bases is the latest trend. One thing that people doing this should keep in mind is that while the gantry itself is very rigid, the overall machine rigidity does depend on the strength of the base as well. Even though the wood base in the plans is just built from plywood, it is incredibly strong. After I first built the wood base, I turned it on its side, with the electronics door area against the ground. I then climbed on top of it, standing at the extreme unsupported cantilevered part. And jumped up and down. It felt like jumping on a solid block of wood. It is very, very stiff.

Not that I'm implying that your base doesn't look strong enough. I'm just saying that anyone building a steel base should make sure there is no perceptible flexing between the side uprights.

Keep up the good work, its looking very nice. And keep posting pics, please!

-Bob

[TeslaFreakshow]

Hey Bob,

Thanks for the compliments. A few days before I got the metal I slapped together a jig to hold the beams perfectly 90 while I tack welded them. I owe the fast progress to that thing. I tacked the whole thing and then rotated welds all over. I welded the inner welds really well and ground all the butt welds off. Im pretty anxious to get it running Ive got a bunch of stuff I want it to cut.

It doesnt look that strong but I resisted the urge to add anymore beams for now. I figure if its not rigid enough after ive got it built and running ill skin the sides or add a few supports or perhaps both. For some reason I didnt trust my wood skills enough. Seems like lately whenever I use wood something is cracked or warped or mis aligns when I drive in a screw.

Last night I was able to make 5 or so parts. Hopefully this comming weekend I can knock out all the alu parts since I have 4 days off.

[TeslaFreakshow]

Hi Tom,

Wow, that is quick progress. That's a very attractive frame. Nice build quality. What is your plan is to mount the stepper motor?

It seems like building welded steel bases is the latest trend. One thing that people doing this should keep in mind is that while the gantry itself is very rigid, the overall machine rigidity does depend on the strength of the base as well. Even though the wood base in the plans is just built from plywood, it is incredibly strong. After I first built the wood base, I turned it on its side, with the electronics door area against the ground. I then climbed on top of it, standing at the extreme unsupported cantilevered part. And jumped up and down. It felt like jumping on a solid block of wood. It is very, very stiff.

Not that I'm implying that your base doesn't look strong enough. I'm just saying that anyone building a steel base should make sure there is no perceptible flexing between the side uprights.

Keep up the good work, its looking very nice. And keep posting pics, please!

-Bob

Forgot to mention. As far as teh stepper I thogh I would just extend the motor plate beyond the frame and have the stepper hanging off the back. Im thinking I might change out that piece to steel so its stiffer.

[revwarguy]

May I ask what the overall dimensions are and the wall thickness of the tubing?

TIA,

[TeslaFreakshow]

Off the top of my head it is 25.313 from rail to rail measuring from the inside. Depth is 30 inches height is 11.375 on the right and 11.5 on the left. I tried to keep everything but depth the exact same. The wall thickness is .0625 of the tubes and they are 1.25 inches square. I might skin the insides of the frame with sheet metal later on but ill probably test it as is.

-Tom

[TeslaFreakshow]

So here is where am at so far. I haven't gotten a router, anti backlash nuts motors or stepper driver and I still haven't made the router clamp. Partially because I haven't gotten the router and also because I'm procrastinating on it. Not looking forward to making it. Not sure what router I'm going to buy.

I also didn't bother lock tighting any rods yet because I was afraid I'd have to remove some of them. I might test it without it and see what happens.

Somehow I ended up having a couple set screw holes on the wrong side of the parts and had to redrill and tap them on the other side.



-Tom

[antisubae]

Somehow I ended up having a couple set screw holes on the wrong side of the parts and had to redrill and tap them on the other side.
-Tom

Don't feel bad - you're definitely not the only person who's experienced this particular problem.

[momus_cnc]

I still haven't made the router clamp. Partially because I haven't gotten the router and also because I'm procrastinating on it. Not looking forward to making it.

Yeah, it is quite a bit of whittling away at a hunk of aluminum to make those parts. The best solution is to contact billj about buying a set. He's been producing them in both aluminum and derlin. When you consider the time involved in making them by hand, I'd say it is money well spent. And it is kind of cool having a beautiful set of parts that were machined on a version of what you are constructing.

By the way, you are making really fast progress. And it is looking great! Keep the photos coming.

-Bob

[hedgehog23]

yes im injoying this build too as im no wood worker. i bought the plans a few days ago and am thinking a welded tube frame is the way to go. lined with 1/8" plate and a wood or aluminum base is the way to go.

[TeslaFreakshow]

Hi All,

Lost my job a week ago so im trying to hurry and finish this before i run out of money. I'm overly anxious to get it cranking out parts.

antisubae,

I wasn't sure if it was the plans maybe the views not being consistent but its an easy fix so I didn't even bother really looking into it. I actually drilled and tapped new holes with everything still mounted.

Bob,

I might just ask him when i'm ready seems like a good idea. Ill wait till after I buy the router itll probably be the last thing I get.

I'm still a little worried about the alignment. My drill press vice kinda sucks and the first couple of parts I made were less then perfect. So far everything slides smoothly though.

hedgehog23,

I think so too but drawing it up in Autocad first or something isn't a bad idea. That's what i did. Also it wouldn't be a bad idea to make it a quarter inch or so narrower on the width. I had 12 washers on each left gantry bearing. I ran out of them then replaced them with one locknut. Worked out perfect.

-Tom

[hedgehog23]

interesting. ill wait to build the "box" until after the gantry is finished. that way i can take "real time" measurements and get it bang on.