[bjesson]

Post modification, upgrades, and Ideas here!

[bjesson]

Some of the mods I am using are not neccessary to do as we all have different uses in mind for our Momus desgn CNC router. But, it will be interesting to see what others are doing to their machine to either improve it for their specific application or to change around different routers/steppers/electronics/etc.

So far I have only made one actual modification and tested out two different routers.

Modification #1: Carriage primary bolts.

I have posted this in another thread but to get everything into one obvious location I will post it once more. Modifying the carriage bolts that sandwitch parts #16, #22, #23 and the four spacers it not neccessary for a general build. In my case I was cutting a lot of metal and plastics and at certain depths and feedrates my carriage was getting shifted out of alignment. When tightening the bolts on the 1/4-20 studs They would break before I could get close to what I felt was sufficient torque. It took a few hours of tearing down, drilling, putting back together and aligning but it has greatly improved the rigidity and strength of my carriage. I replaced the 1/4-20 studs with 5/8-16 caphead screws and bolts.

Bosch Router:
Originally I thought the bulier size of the Bosch Colt was going to cause some problems but now I have completely reversed my decision. Since my CNC has been built for over a month now it has been very easy to create clamps out of delrin and test them all within a few hours time. So, I created clamps for the Rigid 2401 router since the plans are designed for the 2400 model the clamps in the plans required some re-engineering. A perfectly match pair of clamps made bit alignment easy and dead-on. So I moved to testing out the Bosch since I already own one and was originally going to use it until I found I didnt have the right material to mount it at the time I was fabricating parts. Took a day to create the gcode and cut the clamps, mounted them late at night and spite one measurement off (easily fixed by a spacer) they worked out perfect. The Bosch has a 3/4 inch aluminum section at the spindle end that completely surrounds the spindle and bearing. the Rigid is all plastic at this location. price wise they are both about $110 brand new. I have now tested both routers running same programs in three different materials and my opinion is the Bosch outperforms the Rigid by quite a bit. Don't worry though, the Rigid will work out fine for just about anything you can throw at it but if you have the extra time and money the Bosch, in my opinion, would be a good upgrade.

Billj

[Michael In Cali]

What do you think of perhaps deleting item 26 (z-rail block) so one could pull the router back inboard a bit. One would have to modifiy the lead screw nut attachment. Is there enough room?

[kemper45]

I have not been able to figure out a way install stud SB (fourth from top) which joins part 26 (z rail block) to part 25 (z rail) and the back stud SA for parts 27 and 28 (nut plate block and nut plate). The heads of the 2 studs seem to interfere with each other to me. Right now I don't have the SA stud installed. The modification that makes the most sense to me would be to lower stud SB.

Dave

[bjesson]

What do you think of perhaps deleting item 26 (z-rail block) so one could pull the router back inboard a bit. One would have to modifiy the lead screw nut attachment. Is there enough room?

It could be done but then you would have to change dimensions on the clamps and the Z-drive flange mount as you said. Also part 26 acts as a stiffener for the Z plate, you could essentially cause more issues. I thought the bigger body router would cause problems since it leaned out a bit more but after building the clamps and mounting I don't see any issues at all. I think the key here is to have very precise and strong clamps. If it helps I will throw the mechanical drawings up later on this post and I will also be cutting some aluminum and/or delrin clamps for other Momus builders to purchase at a small fee (Time and Costs).

billj

[bjesson]

I have not been able to figure out a way install stud SB (fourth from top) which joins part 26 (z rail block) to part 25 (z rail) and the back stud SA for parts 27 and 28 (nut plate block and nut plate). The heads of the 2 studs seem to interfere with each other to me. Right now I don't have the SA stud installed. The modification that makes the most sense to me would be to lower stud SB.

Dave

Stud SB on the Z-rail is a tight fit and a major optical illusion. This stud has to be exactly the length from the stud schedule and maybe even a hair shorter. What I did was mount the Zrail block to the Z rail then bolted the nut plate to the nut plate block, then bolted the nut plate/plock assemble to the Z-rail assembly and all fit fine. If you are having issues you can use a 1 inch socket head cap screw, washer, and blue threadlock for stud SB on the Z-rail, this will give you a bit more clearance. You could probably do the same for the nut block/plate as well. I accidentally broke stud SF which is above SB and replaced it with a cap screw and it works fine.

If you havnt drilled and tapped yet then you can definately lower stud SB a bit, if you already drilled/tapped everything then cap screws will do it.

Billj

[fastpcuser]

What about using V-grooved rails and bearings. could be easier to hold aligment for XYZ travels. And maybe we could remove those side bearings on X axis by the motor ?

[Michael In Cali]

You could do that, but at added cost cost and volume. V-bearings and eccentric bushings are not cheap and will take up more room.

Before coming across this machine design, I was looking at V-bearings. This is simply more elegant for its intended use and price point.

[fastpcuser]

Another thought what about adding SuperPID controller since Cutting plastic or aluminum at 20000rpm is really not good idea.

Except SuperPID is kind of expensive

[revwarguy]

I have a SuperPID with a modded Bosch Colt, and I love it. The Colt turns at 33,000 rpm, which means it is really, really loud. There are two verisons - one with and without speed control. The problem with this kind of speed control (and the other add-on ones) is that they work by setting the AC voltage to the router, which means that it also drops power. At lower speeds you may not have enough power to cut wood without tearing. The SuperPID allows you to set the speed, not the voltage by using feedback that continuously adjusts voltage (power) to maintain a given speed setting. This feedback comes from modding (voiding the warranty ) an rpm sensor on the unit. I've cut polycarbonate, pvc, acrylic and acetal (Delrin) without burning or melting, as well as a couple different alloys of aluminum and brass. With it, you can run a test cut on a new material, and dial in to find a sweet spot speed setting (at a specific doc) where the chips fly with no vibration or melting.

I can now have a conversation with someone while the machine runs!

"since Cutting plastic or aluminum at 20000rpm is really not good idea."

This depends - I've cut aluminum and plastic at that speed that left a perfect surface. Depends on bit (number of cutting edges especially), doc, feed rate, etc.

[ldanut]

Does tha gantry can hold a spindle like this :

CNC-Plus Germany - AW-FSE 1050 Frässpindel

It weight 2.6kg.

[bjesson]

been working on this for a few days, took longer to anodize then machine I think. I rebuilt the carriage, changing it from an 8 piece (4 rails and 4 spacers) to a 4 piece (4 rails, integrated spacers). I did this for two reasons:

First: I hate having to remove the gantry to slide the carriage off.
Second: I wanted a more rigid carriage assembly.

So, I hopped on the NC mill and made a matched pair of #16 rails keyed to the new #23 and #24 rails with the integrated spacers. Now I can remove the carriage assemble without removing the gantry and there are no extra steps required to square the carriage, it is self-aligning. Since all four parts are integrated there is zero chance of racking.

Tell me what you think....

[bjesson]

Last thing, I changed the four clamping posts to 5/16-18 all-thread with full insertion. I tapped from the top of the spacer to the bottom of the rail to get quite a bit more of holding force on the studs. The 1/4-20 studs are all full insertion, I opted not to do the countersink.

Billj

[momus_cnc]

Tell me what you think....

Oh my, that's nice.

[fastpcuser]

Looks good..... where is my set ?

[bjesson]

Looks good..... where is my set ?

You can always PM me if you are interested

billj

[bjesson]

Oh my, that's nice.

Thank You The anodize was just me showboating

This carriage wasnt made for the current machine, it is for the new precision version. The end rails are the next up for mods using your same design with more integration and bulk.

billj

[kemper45]

This carriage wasnt made for the current machine, it is for the new precision version.

Jeez Bill I can't get one of these finished in who knows how many months and you are working on a second one.

Looks great

Cheers, Dave

[momus_cnc]

Bill,

Based on your other postings, I'm assuming that this new machine is the one that will have leadscrews on X and Y. Care to share what you are planning? Type, diameter, pitch, etc.?

What kind of overall accuracy/precision/resolution numbers are you aiming for?

I'm looking forward to seeing this build progress.

-Bob

[bjesson]

Bob,

Doing this in steps. This second machine will have a little more added work area for X and Y with some mods done to the bearing positions similar to what I did with the carriage. The carriage for the most part will not get any further changes, I just wanted it more rigid and easier to remove without disassembling the entire gantry. The next parts will be the rails that hold the bearings to the X rails. Instead of two pieces (top and bottom) I will be making them one piece as well with the centers cut-out to slide them onto the gantry squarely. Shouldn't need a square to align at each end. Also on the left side I will integrate the Y belt bearing mount. I also will stiffen up the gantry for the added length. Once everything is built and working I will change out the belts for the screw-drive. Most of the screw-drive design is still in my head and will most likely use 1/2" acme with a bearing at one end and the stepper at the other, won't know til I CAD it all. New stepper mounts will have to be designed but that is the easy part. I will still use the anti-backlash nut but plan to use a few more things to try to completely remove any chance of backlash. Again, those revisions are about a month out. Want to build the bigger machine first, make sure it does what I want, then move to changing the design a bit (mostly for fun). As far as accuracy, unfortunately as long as I am using steppers then I am at the mercy of the manufacturer plus whatever I introduce, more on this when the time comes. Was thinking of servo motors/encoders to really tighten things up but still debating if the cost is neccessary since I really only built the machine to do guitar bodies. The metal machining was just an added bonus and amplified the addiction. Since I will be doing more machining on this over the next few days I will create a new build thread for it. I was going to strip the first machine down but at this point with two carriages I have opted to build a whole new one. Who knows, I may sell the first one to recover the cost for the second Anyone interested

Billj

Bill,

Based on your other postings, I'm assuming that this new machine is the one that will have leadscrews on X and Y. Care to share what you are planning? Type, diameter, pitch, etc.?

What kind of overall accuracy/precision/resolution numbers are you aiming for?

I'm looking forward to seeing this build progress.

-Bob