New to me CNC

[ddmckee54]

It's been decent outside. so I've been spending a little time picking up sticks and leaves. But I have made a little progress and crossed 1 or 2 more items off the ToDo list, I've got the bed/bearing mounts bolted to the bearings. I wound up cutting about 4mm off the vertical leg of the aluminum angle.


I'm still not sure just exactly how I'm going to bolt the bed to the brackets yet. If I use an M5 SHCS, that will block off those slots for use by the clamps. An M5 FH would work, but my counter-sink bits are either too big for the slot, or too small for the screw head. I may have to resort to using a drill bit for a counter-sink bit.

[ddmckee54]

A kind soul on another forum gave me some possible ways to mount the bed to the brackets, including a couple of links. It definitely pointed me in the right direction.

That led me to a trail of bread crumbs, which told me that I needed to measure the slot width - it's 8mm. Searching for an 8mm t-slot nut with an M5 thread led me to the fact that 8mm is the width of the slot on a 3030 extrusion. Searching for 3030 T-slot nuts led me to this, 3030 T-nuts. Which allowed me to verify that these T-nuts had mostly the same dimensions as the ones that came with the clamps, the T-nuts in the link are M5 - the ones from the clamps are M6. (I've got enough issues with M5 screws, M6 would be worse.) One "Buy it now" transaction later and VIOLA, I have a plethora of T-nuts on the way. Although mounting the bed to the brackets, and the X-axis lead-nut to the bed, will take a healthy bite out of that plethora - I should have enough left over to allow me to clamp objects to the bed for years to come.

I also got my M5 grease zerks today, more stuff that can come off the ToDo list.

[ddmckee54]

Houston, we have a problem. I thought I would have enough clearance between the bearing block and the base for the zerk fitting - I don't. I need about 10mm for the fitting to clear, I've only got 4mm. Initially I thought I could flip the bearing blocks 180 degrees, and have the zerk fitting on top. No can do, the bed overhangs the fittings - so they wouldn't be accessible. I couldn't do it anyway, there's only 8mm between the bearing and the bed. I can't use an angled zerk fitting either, because they're even taller than the straight fitting.

Soooo..... The solution is simple, I install the grease fitting, grease the bearing, remove the grease fitting, and plug the hole with an M5 set screw - 4 times.

[Zabco]

Instead of a zerk fitting would a button head ball fitting work? This one only needs about 2mm of clearance once installed. https://www.mcmaster.com/1102K93/

[ddmckee54]

Thanks for the idea. I've got some M5 flush grease fittings on the way, Along with a grease gun adapter kit that'll fit them, and will also make repacking bearings a little easier.

[Blender]

Originally Posted by Zabco

Instead of a zerk fitting would a button head ball fitting work? This one only needs about 2mm of clearance once installed. https://www.mcmaster.com/1102K93/

That's a nice part. I'd try and be fancy and sink the head into a counterbore. Added complexity for style points that no one can see is a lost trait.


Everytime i see a post in this thread I'm anxious to see a video of it cutting. Getting closer and closer.

[ddmckee54]

Blender:

Maybe in the future, after I get this guy operational, I'll go for the extra style points from the counter-bored bearing blocks. There MIGHT even be enough extra meat on the bearing block to allow a standard zerk fitting to be installed in a counterbore. Until then I'll just go with the flush zerk fittings.

One of the first jobs on the list of projects for this guy will be to carve out new, taller, side plates for the Y axis rails. I'd like to get about 100mm of usable Z axis travel, instead of the 60-ish mm that I have now. That'll be after I get the aluminum parts carved out for the RT7R though. Let's see, that's 16 idler bogie side plates, 4 dump bed pivot brackets, 2 drive motor mounting plates, trimming 2 main rails to size and boring the holes in the appropriate locations, and whatever else I can think of.

I've started on the second page of the ToDo list, but for some reason the list keeps expanding. It COULD be due to scope creep - but I'm pretty sure the shop gnomes are actually who's responsible for that.

[ddmckee54]

Most of the nuts and bolts that I'll need have arrived and I got the bed bolted to the bed/bearing mounts last night. I centered the bed between the rails. The frame diagonals are as equal as I can measure with a metric tape measure, and the edge of the bed is flush with end of the frame, so the bed slots SHOULD be perpendicular to the X axis. If they aren't - well that's future Don's problem. A kind soul on another forum suggested flush zerk fittings. I found some M5 fittings that should fit and ordered them, they arrived today, I should have about 2mm of clearance between the fitting and the base - it worked like a champ.

I'm almost done with the Z axis slider redesign to fit the 300W spindle, something that would have had to happen anyway - might as well get it over with now. I've also been working on the design for the X axis lead-nut block. If I've counted on my fingers and toes correctly, I should have about a 3mm gap between the lead-nut block and the bottom of the bed. I plan on measuring that gap with a stack of feeler gages, and printing a shim to fit. That should be close enough for gubmint work.

[Zabco]

Sounds like it's starting to come together. Hopefully your past the 'surprise' state.

[ddmckee54]

I need to do a little metal-working next, 3 lead-nut mounting plates out of 1/8" HRS - cuz it's the easiest thing to get around here without going online, and the Z axis carriage/Y axis bearing mounting plate out of 1/4" aluminum plate - that 1/4" plate I've already got. I also need to get the printer cranking out some parts, the Z axis carriage parts, and the X axis lead-nut mounting block parts.

While typing this I realized that I need to partially take the bed apart - again. Somebody, un-named at this time - but his initials are probably DDM, forgot to insert the tee-nuts into the bed slots for the X axis lead-nut.

Fortunately, that won't be that big of a deal. I don't even need to actually remove the bed/bearing mounting bracket from the bed, but I do need to take the bed off the rails. That requires taking out 4 bolts, removing the end-plate, and sliding the bed off the rails. There's 3 tee-slots on the bottom of the bed, and each mounting bracket is fastened to the bed by 2 bolt/tee-nuts in each slot - or 6 bolts total per bracket. I need to add a total of 4 more tee-nuts to the slots, 2 to each slot since the lead-nut mounting block only uses 2 of the 3 bottom slots. I can remove the 2 bolts for one of the slot on one of the brackets, slide the existing tee-nuts into the center of the bed, slide 2 more tee-nuts into that bed slot from the side, and bolt the bed back down. Rinse. lather, repeat for the 2nd slot and Bob's your auntie. The bracket won't move because it'll always be held in place by the other 4 bolts in the bracket. I USETAWAS thinking that 6 bolts per bracket was overkill, I guess sometimes overkill comes in handy.

[ddmckee54]

Over the weekend I made the mounting plate for the Z axis carriage and the Y axis bearings. I screwed up when I cut the plate, I didn't cut on the waste side of the line. But that's OK, because I left a 5mm gap between the bearings - so I just squeezed them together a couple of mm. What wasn't OK was the fact that 2 of the 4 holes for EACH of the 4 bearings were in the wrong place. The 2 sets of holes that were perpendicular to the rails had the correct spacing, the 2 sets of mounting holes that were parallel to the rails were not correct. I downloaded the specs for an SBR12UU bearing, which said that the center to center spacing was 28mm - in BOTH directions, Those specs are what I used in my design, and when I made the mounting plate.

When the mounting holes didn't line up I started double checking everything, the drawing said 28mm center to center spacing, the layout lines measured 28mm, the holes measured 28mm on centers. My bearings on the other hand measured 28mm C-C across the rail, and 26mm C-C parallel to the rail. So I started checking to see if maybe I had something different than an SBR12UU bearing. What I found was another SBR12UU spec that matched my bearings. How can the SBR12UU have 2 different specs? I do know how I got 4 bearings that matched one spec and 4 that matched the other spec though. I bought a pair of 1m long 12mm rails with 4 SBR12UU bearings from one supplier. I had to cut the rails to length anyway, so I got rails long enough to get the 2 sets of rails. That supplier didn't offer just the bearings, so I ordered another 4 SBR12UU bearings from another supplier. That also explains why 4 of the bearings needed an M6 grease fitting, and the other 4 needed M5 fittings.

I'm in the process of making a new mounting plate, this time using the correct center to center spacings. The bag of misfit parts will get another donation, but I'm not taking the rap for this one.

[ddmckee54]

I HAD the mounting plate in place for a little while, it's back off again. Past Don apparently forgot that 2 of the mounting holes for the Y axis lead-nut mounting plate SHOULD have been drilled and tapped into the bearing mounting plate for M3 bolts BEFORE it was bolted in place. I've also discovered that I need to be a LOT more careful in my layout and center popping of the hole centers. This mounting plate turned out better than the first one, but I apparently miss-read the vernier on my marking caliper on one row of holes because they were off by about 1/2mm. A little judicious filing corrected that. The funny part is, that was the same row where I had mistaken a scratch in the aluminum for my layout line and all the pilot holes in that row were about 5mm out of place. Fortunately all the extra holes will be covered by the flathead bolt so nobody will ever know about the boo-boo - right? I really can't wait until when I have this thing running, can tell it to go to point X - Y, give me a center mark at that point, and be fairly confident that's where it's actually located - not just sorta close.

It turns out that the depth stop on my drill press is just about worthless when used to get a consistent countersink depth. The only hole that had a good countersink depth was the first one, the only hole I actually verified, the one I used to set the depth stop that I used for the other 15 holes. Because, none of the other 15 countersinks were flush, they all were proud of the surface. I could have lived with them being too deep, but noooo.... I wound up having to take the bolts out one at a time, touch the countersink up with the countersink bit in the hand drill, then put the bolt back in. I don't want to think about how many times I cranked those bolts in and out, before I got the trick down pat of flipping the bolt over and using the head to judge the countersink depth. Remember that judicious filing, and those 4 extra holes? Turns out they are no help at all when it comes time to countersink the hole. They let the countersink wander around like a hotdog in a hallway.

I removed the plate last night and got the hole locations for the leadnut plate mounting bolts laid out. I was going to get them drilled and tapped, but i think I'll hold off on that for a bit. At least until I've got the layout of the leadnut mounting far enough along that I can do a sanity check and see if they'll match.

[ddmckee54]

I spent most of the day double and triple checking the 3D model against the machine as it currently sits, and found a couple of discrepancies - those got corrected. Last week I picked up a piece of 1/8" x 1-1/2" x 48" HRS barstock, only it was 1/8" plate that had been sheared to 1-1/2" width and I'm OK with that. The problem is that for some reason I had modeled this as 34mm wide and it actually measures at 38mm. I fixed the model, but then I had to be sure that everything was in the proper location. which is not as easy as you'd think. The leadnut plate is centered on the Y axis bearing plate, but the leadscrew is not centered on the plate. While I'm changing a LOT on this machine, I tried to move the minimum amount of hardware from its' original location as possible. When I changed the original Y axis 2020 extrusions to 2040 extrusions, I used the original mounting holes as my starting point. I also kept the original location of the Y axis leadscrew, this was not without consequences. By a happy coincidence the centerline of the leadscrew and the centerline of the Y axis rails all align vertically.

However, the leadscrew's horizontal centerline is 3mm below the horizontal centerline of the 2 rails. This leads to an asymmetrical and somewhat goofy looking leadscrew plate. I've got the layout done on the plate and got the holes center popped. I've even got it cut out, filed, and sanded. The layout lines on the Y axis bearing plates match with the layout lines on the leadnut plate. I'm going to drill an 8mm hole for the leadscrew and make sure that's in the right spot before I do anything else. That'll give me a chance to possibly fix it if I did make-a-da-boo-boo. There's not a lot of wiggle room in some areas, the model shows that I SHOULD have about 8-9mm of clearance between base of the Y axis rails and the leadnut plate. The problem is that I didn't model the heads of the mounting bolts for those rails. I've got MAYBE 2mm, but clearance is clearance Clarence.

[ddmckee54]

Ever have one of those Hokey-Pokey days? The days you take one step forward, one step back, then two steps forward? Today was one of those days.

It started out well enough, I got pilot holes drilled every place in the Y axis leadnut plate that needed a hole. Four of the nine holes were locations that needed to be tapped M3, so I just used the M3 tap drill for all the pilot holes. I needed an 11mm hole, actually I need 10.5mm but a little wiggle room isn't going to hurt. I ain't got no metric drills, what I've got are a set of number drills and a set of fractional drills from 1/16" to 1/2" - by 1/64" increments. So far that has fallen well within the tolerances of my gub-mint contracts. Anyhew, I got the big hole drilled, so I could check the leadscrew alignment with the leadnut plate.

Annnndddd.... It didn't fit as planned. I needed to move the plate about 2mm closer to the Y axis extrusions. Which meant that in addition to being too short, the plate is now also interfering with the mounting bolts for the Y axis rails. Oh Happy-Happy Joy-Joy! There IS a silver lining though, I had a proven hole layout, I knew what needed fixing, and I knew how to fix it. The second time you make a part really is faster than the first time, practice makes perfect I guess.

I knew that there was no way on God's green earth that I was going to be able to drill and tap four M3 bolt holes with everything on the rails, so I came up with a work-around. I took a careful measurement of the distance from the edge of the leadnut plate to the edge of the bearing plate, and clamped the leadnut plate in place. After carefully removing both plates, they were transferred to the vise where a transfer punch was used to mark the center of one hole - didn't want to push my luck. After drilling and tapping the hole M3, I used the M3 bolt to clamp the leadnut plate in place to mark the other hole. Rinse-lather-repeat and all the holes in the Y axis bearing plate are now drilled and tapped.

That just leaves the M3 hole that needs to be drilled and tapped in each of the far side Y axis bearing blocks. Back to the machine to partially reassemble the Y axis bearings and bearing block. I didn't need to put EVERYTHING back together, I just needed the far side bearings blocks tight enough that they wouldn't move when I slid the bearings off the rails. I took the side plate off the nearside of the machine, slid the Y axis close to the end of the rails and removed the near side bearings, setting them aside. I was then able to remove the rest of the Y axis assembly from the rails, clamp it firmly in the vise, and use a transfer punch to mark the hole locations for the M3 bolts. I then removed the bearings from the plate, covered the bearing openings with tape to keep the swarf out, and drilled and tapped the holes for M3 bolts. I then started putting this part of the machine back together - for what I hope to God is the last time.

Anywho, this is what the Y axis looks like now.

Like I said, the offset leadscrew makes the plate look a little goofy. Everything is just loosely assembled right now, and since I took the side plate off I'll need to align the rails to the bed again. That's not the actual leadnut, I need to build the anti-backlash nut and the leadnut plate together as an assembly. The four M3 button-heads hold the leadnut plate/leadnut assembly to the rest of the Y axis assembly so maintenance will be fairly easy.

[ddmckee54]

Today was spent putting the Y axis leadnut assembly together. I started with your standard 3D printer anti-backlash leadnut, looks like this when assembled on the leadscrew.


This is just 2 modified leadnuts assembled back to back with a spring between them.. The spring keeps the 2 halves of the nut separated, removing the backlash, and a tab/slot arrangement keeps them in sync. This works fine for the minimal tool pressure of a 3D printer. BUT, and there's always a big butt, any tool pressure that opposes the travel will overpower that wimpy little spring and your backlash is back - don't think that'll do the surface finish any favors.

I remembered that Awesome CNC Freak had modified his 1310 machine to deal with backlash, so I did some digging - and then quite happily swiped his idea. This was the test rig I built.


It proved the concept. By using the nut to squeeze the 2 halves together you eliminate the thread backlash, and it's much more rigid. It does take careful adjustment though, you go from free falling to totally locked up in 1/4 turn of the nut. The bolts I used on the test rig weren't long enough though, the nylocks wouldn't lock - going from M3x35mm to M3x40mm bolts solved that problem. The bolts also keep the 2 halves in cync. This is what the business end of the Y axis anti-backlash leadnut assembly looks like.

That part will be buried between the Y axis bearing blocks though. This is all you'll see.


OK, OK, if you ignore the bit in the lower LH corner - THAT's what you'll see. Really shoulda cropped that picture.

[ddmckee54]

I had a couple of 3D printing milestones recently, I started printing with something other than PLA and the P1S glitched on me. Although in all honesty I probably made it worse than it should have been.

I decided to try PETG, and I wanted to get the scaling dialed in to correct for shrinkage. I decided that I might as well be printing something useful to do this testing. My new spindle uses an ER11 collet, so I found an STL for a chip fan that presses onto the collet nut. The friendly Google AI said the scaling factor should be 100.3-100.8%, so I scaled the fan to 100.5% and gave it a shot, way too tight. I scaled it to 100.8% and printed it again. It takes less than 1/2 hour to print the fan - including the 7+ minutes the P1S uses for setup on every print. It was still too tight, but I could force it on the nut. I printed it again, this time scaled to 101.5%. It presses onto the nut, not all the way, but since I didn't design the fan I can only guess the designers intentions. I WAS going to print a fan scaled to 102%, but that's when the glitch occurred. I started the print and left to do something else. When I came back about 15 minutes later I had a bird's nest on the print bed. It happens, so I did what I do when the D6 screws up late at night - I shut off the power and went to bed.

When I got up the next day and fired up the printer it was not happy with me, the AMS was making very unhappy noises. I realized that I SHOULD have aborted the print, then shut off the power and gone to bed. Ain't 20/20 hindsight just wondermus though? I realized that the filament had frozen in the extruder and that I needed to get it out of the hot end so the AMS could retract it and be happy again. But, I needed to do that before the AMS was powered up. I decided to try unplugging the AMS, heat up the hot end, and see if I could pull the filament back by hand - to see if that would work. I did, and it did - so I decided to try printing again. All seemed to go well, until it tried starting to print about 50mm above the print bed. All I could do was abort the print and hang my head in shame wondering "What the **** did I do to this poor machine?" Before I contacted Bambu Labs and confessed my sins, I wanted to run the initial calibration cycle again. I wanted to see if that would let the printer find its' lost marbles.

I'm proud to report that it worked and the plastic pooping robot is now about 7 hours into an 8 hour print. That print will give me the Z axis rail holder, and the bearing block that will slide on those rails.

Don

[Zabco]

I run PETG exclusively in my Prusa I3Mk3S+. Had this printer for over three years now and have never had a problem with it or a failed print. I don't know why so many people make such an issue over PETG. I pretty much just use the standard settings Prusa supplied for their PETG and just change settings for supports or amount of infill as needed. I use Inland brand which is the in-house brand for Micro-Center. About the only locally available source I have. Sometime I'll have to tell you about all the "sins" I commit using this printer.

[ddmckee54]

Zabco, the first place I worked in industrial maintenance was a plant that made laminated plastic sheets using various core materials and resins. I got firsthand experience with how obnoxious hot plastic can smell. i don't mind PLA, it reminds me of waffles when I print with it. I got a roll of PETG when I got the P1S, since it's enclosed. But the door was broken when I got the P1S and it took a while to get the replacement, so I kept using PLA. Since I replaced the door this is the first time I've had a chance to try the PETG. But even with the door open, there's barely any odor from the PETG.

The Z axis carriage is starting to come together, literally.

The Z axis rail holder was usable, a little oversized but usable - the bearing block was not. Somewhere between the design notes and the cad operator, the understanding got lost that 20mm was the C-C spacing for the mounting holes, and that the remaining 28mm of the 48mm bearing block width was to be used to center the spindle mounting bracket. Somehow the 28mm became the C-C spacing, and the 20mm was split to center the spindle clamp. The 15mm bore for the bearings was over 15.1mm on the unusable part, not exactly a press fit. And NOBODY caught the boo-boo's before the files were cleared for production. When the assembly techs started screaming that the damned thing don't fit and went on break, THAT's when we found it. The rail holder was supposed to be 60mm wide, it measured 60.5mm. I had originally scaled the STL models to 101.5%, I dropped that back to 101.2% when I reprinted the bearing block. I kept the 6 perimeter walls and 80% infill though.

When I reprinted just the bearing block the print time dropped from 8 hours to 3 hours. I accidently ordered M5x70mm bolts, everything was designed around M6 bolts, but these will due for now.

[Zabco]

My first printer was a Makerbot Thing-o-matic. Whopping big 3"x3" bed. Used to use ABS in it. Now there is a plastic that will stink up the place. Went from that to a Lulzbot TAZ6, which at the time had the biggest build plate available at around 12x12. Used primarily nGen on it as that is what Lulzbot claimed they used to print their parts with and they included a test sample to try. Liked nGen alot as it was very low odor and printed very nicely. Much stronger than the ABS. Trouble was the TAZ required 2.85mm filament and the rest of the world was going 1.75mm. Was having to order from wherever I could find a supply. So upgraded to the Prusa. Love that machine. Came with free spools of PLA and PETG. Tried the PETG for first testing and it worked so well that's all I've ever run through that printer. I've never even opened the boxes of PLA. As I said earlier I've never had a failed print yet (knocking on my forehead) and I get terrific quality prints. Prints come out so close to design dimensions that I don't bother with scaling factors. And I can't detect any kind of odor from the PETG. Only downside is it can be a bit brittle. Had to print the same front end loader cab three times because I kept knocking it off the workbench and the narrow areas around the windows would snap when they hit the floor.