[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.

[hedgehog23]

updates?

[TeslaFreakshow]

Yep few updates, I still haven't made the router clamps or bought the router yet. But I did get the belts and pulleys installed finally and I made a stand for the whole thing. I'm probably going to have to dismantle the whole thing and locktite it because I didn't have any when I assembled it. I also finished the bottom and poured the epoxy. Its just made form 3/4 inch plywood.

I got the wrong shaft coupler the one I ordered is 1/4" to 1/4" I needed the 1/4" to 3/8" I also need to figure out how to arrange everything in the garage so the parallel port cable will reach the machine.

[TeslaFreakshow]

Alright well ive finally finished the router clamps. I had a few problems. I widened the clamps to fit the r2401 router and the clamps ended up hitting the acme threaded rod so i cut two notches out of them which im not that happy about.

So everything is pretty much good. i made some test cuts with a .310" diameter somewhat dull single flute router bit. I'm having a problem with the z axis shifting a little one direction after a few cuts. I was cutting some 3/4 inch poplar at about 15 ipm at about .250" depth.
I suspect that my spacer blocks are exactly the same height. I'm thinking of making new ones threading them and then welding them to the z axis carriage blocks. Anyone else have this problem? I can't seem to figure out what IPM is reasonable for this type and thickness of wood

[momus_cnc]

It sounds like what you are describing is the problem of the carriage racking/shifting out of square? This shouldn't be happening, especially at that feed rate in poplar. With a good sharp bit, and that depth of cut, you should be able to push through poplar at 10x that feed rate with no problems with the machine. (not saying that is the correct feedrate for the material, just that the machine should withstand the cutting force with no problems)

A few others have had this problem, and it has been mentioned in a few threads. Basically, the 4 main studs holding the carriage together need to be VERY tight. I'm working on a design change that will provide positive locking between those parts, so they don't rely on just clamping force. But in the meanwhile, the fix is to first make sure the nuts on those studs are as tight as possible, and if a problem persists, then change them out for 5/16” studs or bolts. I took my own machine apart to see just how much difference the 5/16” would make, and it is substantial. You can get them a lot, lot tighter. I also swapped out my homemade spacers for some purchased ones to make sure they were as flat as possible and have parallel faces. I bought them from Quality Aluminum Spacers - Largest Selection on the Web for $1.20 a piece. They are 11/16" long, 5/8" o.d and 3/8" i.d.

Attached are some photos of the upgrade to 5/16” bolts. I was hoping I could do this one bolt at a time without tearing half the carriage apart, but unfortunately that is what I had to do in the end.

First photo is the “before” shot of the original spacers and studs.

Next photo is of the new parts. 5/16” grade 8 bolts, nuts and washers.

A testament to the strength of the loctite. One of the studs snapped while trying to remove it. This meant I had to remove all of the bearing from this piece so I could heat it up with a propane torch to soften the threadlocker. Luckily there was just enough stud to grab onto it with a pair of vise-grips. Once the studs were out, I just drilled out the holes through all the parts for the larger diameter bolts.

Last shots are the new bolts and spacers in place.

With the new 5/16” bolts I can drive the collet of the router sideways against a block clamped to the bed of the machine, and the steppers will stall before the carriage shifts. And that is with my Gecko G540 drive and 381 oz/in motors, which have gobs of power.

-Bob

[GTFreeFlyer]

Awesome, I just bought those spacers. That'll save me some time. Any news on when to expect the plans update to come along?

[SpeedyDad]

Yeah, I just ordered the spacers too. Figured I might as well upgrade my carriage since I haven't aligned it yet.

[TeslaFreakshow]

Sweet, better than trying to make new ones. I was going to borrow someones mill and do them that way but this is much easier.

[momus_cnc]

Any news on when to expect the plans update to come along?

It won't be for a while. Many months, most likely. There are enough changes that I will be needing to construct another full machine to test them all out. My plan is to post many of the changes here first, as I work on them one at at time. Many of them will be things that are backwards compatible and can be retrofit to the existing machine, and in those cases I'll post new drawing sheets and any other needed info (like the limit switch info I posted a couple of days ago, which even included G-code). That will also help me get some feedback on the changes before I incorporate them into the plans.

-Bob