It's new to me

[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.

[vtsteam]

Thanks greatly for pics! 

[ddmckee54]

Thanks greatly for pics! 

I had my old Blueberry flip-phone for so long, I keep forgetting that my new flip-phone has a camera.  It doesn't have the anti-blur capability of my camera so sometimes it takes several attempts to get a decent shot.

[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 Hell 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

[ddmckee54]

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 spaving, 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 that 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.

[vtsteam]

Yipes, a string of bad luck! I'm sure you'll get it working soon.

This is what I hate about trying to program absolutely everything in advance, as opposed to measuring and cutting during fabrication. Not that fabrication isn't also subject to errors, but with work in hand, often times you can try pieces against each other, or mark from each other, or quickly measure a fastener and the drill bit you are planning to drill it with, etc.

Some people work better one way, others vary from that. I find I make fewer errors in manual work than I do in additive machining, because the latter demands advance perfect location of all features or a part is often ruined. One frequent problem in an imperfect initial rendering: since infill is usually partial to save material and time, relocating or even resizing a hole or other feature is often not feasible.

Nevertheless, I admire anybody who makes the effort by this or any other means and manages to create something in our hobby. I'm sure this mill project will provide rewards when it starts machining other parts! 

[ddmckee54]

A couple days ago I decided that I really didn't want to wait for more bolts to arrive from an online order to replace the M5x70mm bolts.  My local farm store has a good supply of both Imperial and Metric hardware hardware, that they sell by the pound, not per unit.  Unfortunately anything below 1/4" in imperial, and M6 in metric is sold per unit.  And they don't have socket head cap screws, but I decided I could live with hex head bolts for the spindle clamp.  I found the M6x70mm bin and grabbed 4 bolts.  Unfortunately they did NOT have M6 nylock nuts in bulk.  I got all four of the M6x70mm bolts I needed for less than what one of the M6 nylocks cost me.  While I was checking out, and the checkout lady was scanning the barcode of all the individual plastic packages, I mentioned that all of the nylock nuts should be the same.  She replied that one of them was an M5...  Back to the hardware drawer with the M5 nylock - to get what was the LAST M6 nylock.  Don't blame me, the bin said M6 nylock and we're supposed to trust that - right?

This afternoon after getting the last 0.6mm of extra length removed from the the 8mm Z axis guide rails, I discovered that one of my M6 bolts was not 70mm long, it was only 60mm.  Soooo..... back to the farm store with the 60mm bolt to get a 70mm bolt.  Don't blame me, the bin said M6x70mm and we're supposed to trust that - right?  Since I was already out and about, I decided that I might as well go to the grocery store to get some more chocolate syrup.  I like my ice cream, but I like it with chocolate syrup and nuts.  Funny how you go to the store for one thing, and usually walk out with a lot more than just the one item.  I got the screws installed that retain the bearings in their bores, all that's left to do on the Z carriage before its' final assembly is to install the heat set M3 inserts for the leadnut mounting plate.

Tomorrow I'll get the X axis leadnut block printing before I do anything else.  While that's printing I can get the heat set inserts installed on the Z carriage, and start working on the X and Z axis leadnut plates.  I finally broke down and ordered some Dykem, magic markers work - butt...

Geez-Louise, pretty soon I'll be down to the fun part - the electrical install and de-bug.

[ddmckee54]

OK, time to Fess up, I make-da-nuther-boo-boo. For some reason I designed the mounting bolts for the Z axis NEMA17 stepper motor to use heat set M3 inserts. Normally that shouldn't be a problem. HOWEVER, the NEMA17 motor mounting locations are M3 threaded blind holes. Something tells me that four M3 threaded blind holes facing four M3 threaded blind holes just ain't gonna work to hold the motor in place.

The Z carriage was printed with 80% infill so you would think that if I could just drill the blind holes through with no problem. That actually would work for the two holes closest to the rails. The other two holes however would still be buried in the upright section of the carriage. That's probably what caused the brain-fart of thinking I could get away with using the M3 threaded inserts in a blind hole. Nope, I need to redesign the Z carriage. It's nothing serious, I just need to move the rails, leadscrew, and everything associated with them about 10-12mm farther away from the upright section.

The X axis leadnut block is printing now, by the time it gets done I SHOULD have the changes ready to go. The plan is to get the carriage reprinting by the time I go to bed.

[AdeV]

I dread to think how many hours if printer time & reels of filament I've wasted on mis-designed parts... And I don't mean failed prints, I do mean where there was a design error...

I don't mind heat-set inserts, but I try use an alternative all-printed mechanism wherever possible - but obviously they can't always be realistically avoided. I did manage to design (and successfully print) a box which snaps together & never comes apart again (not without taking damage anyway) - not always what you want, but it works for my use case.

I'm still following along with great interest... although I may have cheated over here & spent out ?1250 on a refurbished Boxford mini CNC milling machine... seemed like a quicker solution to me! Now I just need to buy a new house so I've got room to actually use it!

[ddmckee54]

I got the X axis leadnut block printed along with the new Z carriage, and the heatset inserts have been installed.  I thought that I had assembled the Z carriage for the final time, but I was mistaken.  I haven't greased the linear bearings yet, so I'll have to partially take it apart to grease it.  One of the things I did during the design for my upgrades, was to make sure Future Don wasn't going to curse my name when it's time to service this thing.  I'll need to remove the rails to grease the bearings, but it's possible to do that and not lose the alignment.  By removing the stepper motor and the two screws retaining the upper end of the rails, it's possible to pull the rails out the top of the carriage.  The spindle, spindle clamp, and the bearing block can then be removed as one unit.  Since none of the bolts holding the critical alignments in place need to be loosened, the alignment shouldn't change.

I've got the carriage roughly aligned to the bed, meaning that it's as square to the bed as my square and my Mk1 eyeballs can make it.  The final alignment won't happen until I've got this thing moving under it's own power.  Then I can use a DTI and a 123 block to really dial things in.  This is the current condition of the Z carriage.


The X axis leadnut is currently bolted to the bottom of the bed, I kind of got ahead of myself when I did that.  I guess it's a good thing that I made it easy to remove the bed to work on the bottom of it.  Just remove the four bolts holding the endplate on and the bed can be slid off the rails - bed alignment is not affected.

I need to get a measurement of the distance between the top of the leadnut block and the bottom of the bed, with the leadnut block assembled on the leadscrew.  If I did the "Plottin-N-Conivin" right, that distance should measure around 3mm.  BUT,...  I can't measure the distance until the leadnut block is assembled on the leadscrew.  That can't happen until the anti-backlash nut is assembled and adjusted.  And THAT can't happen until the leadnut plate is fabricated.  And since the X axis and Z axis leadnut plates are very similar, I might as well do them at the same time.  That'll be happening next.

[ddmckee54]

The weather was nice for the last couple of days, so I've been harvesting my first crop of dandelions of the season.  I hope it's the last one too, but I'm not gonna hold my breath.  Anywho, I managed to get a little more work done on the CNC.

These will be the leadnut plates for the X and Z axis when completed.  The lower plate, the X axis leadnut plate, is 38x38mm.   The upper plate is the Z axis leadnut plate and it's 24x27mm.  Why the different sizes?  Originally, all three leadnut plates were SUPPOSED to be identical to the X axis plate.  The Machine Gods laughed at my plan and sent their minion Murphy to curse my design choices.  That's my story and I'm sticking with it.

Despite their different sizes, the plates are very similar.  They each get nine holes.  The central hole needs to be in the 10.5-11mm range.  Ain't got no stinkin' metric drills, I got fractional drills and number drills.  A 27/64" drill is just under 10.72mm, that's close enough for this Gubmint contract.  There are four holes on a 16mm bolt circle that will be tapped M3.  That requires either a 2.5mm drill - which I ain't got, or a #39 drill - which I've got.  The last four holes are M3 clearance holes.  A 9/64" bit will give me a fit that falls between a normal fit and a loose fit - it works for me.  A little extra clearance never hurt Clarence.

[ddmckee54]

Sometimes I'm just not as smart as I think I am...

I got the Z axis leadnut plate drilled and tapped in the appropriate places, I also managed to snap off my M3 spiral tap in the process. While running the tap in far enough to be sure all the chips were cleared out of the threads, I ran the spiral tap through the plate. While trying to start the tap back into the hole I managed to get it started crooked, and snapped it off. Fortunately there was plenty of the broken tap sticking out of the back of the plate that I could grab onto and thread it out. I had one other M3 tap, a 4 flute tap, and wanted to chase the threads - but I didn't want a repeat of the previous disaster. So I drilled a clearance hole in a piece scrap plastic and made a simple M3 tap guide. I used that to chase the threads, and also to tap the one remaining M3 hole on the Z axis leadnut plate.

I then set about assembling the anti-backlash leadnut, and getting it adjusted. The process I used to assemble/adjust the Y axis leadnut is identical for all three leadnuts; the only thing that varies is the shape of the leadnut plate. So... Onto installing the leadnut into the spindle slide.

Anddddd... it doesn't fit. Oh, it fits into the pocket alright, it's just that ALL of the leadnut doesn't fit into the pocket. The top of the leadnut plate is still 1-2mm proud of the surface and it should be flush.

The cause of this evil deed? When assembling the Y axis leadnut I discovered that when using the M3x35mm bolts as originally designed, if the two halves of the leadnut weren't clocked properly, I either couldn't assemble the leadnut halves or the nylock adjusting nuts wouldn't lock. My leadscrews are T8 2 start screws, with a 4mm pitch. With the Y axis leadnut, the only way the M3x35mm screws would work was if the 2 halves of the leadnut were threaded so close together that I couldn't remove the backlash in the threads. Clocking the 2nd half of the leadnut to the other start moves that half by 2mm, which allowed me to adjust out the backlash. Unfortunately, that also moved the adjusting nut by 2mm, far enough that the nylon locking ring wasn't doing its' job. I had M3x40mm screws, which solved that problem. What it didn't solve was that the pocket the leadnut fits into on the spindle slide had 2mm of clearance - when using an M3x35mm screw.

Sometimes I'm just not as smart as I think I am.

[ddmckee54]

OKAY.... The reprinted spindle slide is finally done, and this time it worked.  I modified the depth of the pocket for the leadnut assembly.  I had forgotten about the screws to hold the bearings in place on the first iteration and had manually drilled the screw holes.  I modeled those in, and I reduced the bore of the holes for the linear bearings from 15mm to 14.9mm.  It didn't work the first time I reprinted the spindle slide though, but that was operator error.  The first time I had started the print before I went to bed, when I got up the next l morning I ASSUMED the print was complete and popped the print off the build plate.  When I started examining the print I realized it was missing something, like the top 3mm of the print.  It was about this time that I realized the  print wasn't DONE, it had run out of filament and paused itself - waiting for me to add more filament.  Whoopsie, would have been nice if I had remembered the printer could do that BEFORE I ripped the print off the build plate.

OKEE-DOKEE, I aborted the paused print, added a fresh roll of filament, and started a new print.  I also ordered 2 more rolls of grey PETG filament, 'cause I'm really liking this stuff and I gonna reprint the RT7R in PETG.

[ddmckee54]

I got my roll of Mango Yellow PETG today, so I can start reprinting the RT7R's yellow parts anytime.  It's a little darker than the Gold PLA I was using, and the Bruder Yellow - but I'll live with it. 

On the CNC front, I got the X axis leadnut plate drilled and tapped yesterday, today I got the X axis leadnut assembly assembled and adjusted.  I also got the Z axis put back together - mostly.  I still have to cut the spare leadscrew to length and get it installed.  If I take the lower leadscrew bearing out, I think I'll have enough room to be able to install the leadscrew that way.  If not, I'll be taking the spindle slide and rails out one more time.  Yesterday I also got the drag chain I'm going to use for the X axis.  My choices were: 10mmx15mm, 10mmx20mm, 15mmx30mm, or larger.  My cables are 7mm in diameter, I need 22AWG - 6 conductor shielded cable for the steppers.  I actually only need 4 conductors for the stepper - but I'll need 6 conductors to install the MKS42 stepper/servo conversion kit.  (I am NOT using that unshielded 28AWG ribbon cable!)  I've got 16AWG - 2 conductor shielded cable for the spindle motor.  I'll need a 3rd cable if I ever install homing and/or min/max travel limit switches.  The 10x15 drag chain would handle 1 cable with no problem, 2 would fit but it'd be tight, MAYBE 3 if you zig-zag stacked them, but it wouldn't be pretty.  The 15x30 chain is what I ordered.

[ddmckee54]

Mechanically, this is starting to come together.  I got the Z leadscrew cut to length, I installed the Z leadscrew, I disassembled the bed enough to remove the X leadnut block, I installed the X leadnut assembly in the leadnut block, and I reassembled the machine enough to measure the gap between the bed and the top of the leadnut block.  When I designed the leadnut block I wanted to be sure that my block wasn't too high, so I subtracted 3mm from what I had sketched out and printed the block.  I must have already subtracted that 3mm when I drew the sketch, because when I measured the gap it was 6.17mm.  It's no big deal, I'll just print a 6+ mm shim instead of a 3+ mm shim.  Here's a view of the gap from the motor end of the leadscrew.


This is a view from the other end of the leadscrew.


One thing I discovered when assembling the Z leadscrew is that the 84 oz-in stepper motor shafts are about 10-15mm longer than the original motor shafts were.  That gap you see between the blue coupler and the Z axis motor shouldn't be there.  I'm going to lose about 10-15mm of travel on all three axis when I install the larger motors.

[ddmckee54]

I was assuming that the motor shafts had been hardened, but I tried a file on one and it cut.  The hacksaw made fairly quick work of whacking 10mm off the end - so I guess I was wrong about the hardness.  I found that the Z carriage will flex.  If I can make it move by pushing on it - it'll move under load.

I'm in the process of redesigning both the slide and the carriage.  I'm going to bolt 1/8"x1-1/2" HRS on both sides of the carriage to keep it from flexing.  Since my carriage mounting plate is 84-ish mm wide, the spindle slide is 90mm wide, the carriage is 60mm wide, and I've only got 24mm from the carriage mounting plate to the back of the spindle slide when I need 40mm...  I need to play around with the numbers, get creative, and see how things look in the 3D model.

[ddmckee54]

I got the spindle slide and the Z carriage reprinted, I even designed and printed the X axis leadnut block, That should be the last of the mechanical parts that need to be printed - I think!

I took the bed back apart, installed the leadnut block shim, and put it back together. There's a little binding as the leadnut approaches the motor end, it's not as noticeable at the other end. I just centered the leadnut block between the bearings, and I suspect that it's not quite lined up correctly side to side. The T8 leadscrew WILL flex, that's why I don't notice the drag when the bed is in the center of its' travel. When the bed reaches the end of it's travel to the motor end, the non-adjustable end of the leadnut is only a few mm away from the motor coupling. When the bed reaches the end of its' travel in the other direction, there's still about 80-100mm of leadscrew between the leadscrew support bearing and the non-adjustable end of the leadnut. That 80-100mm of leadscrew would explain why I notice the drag at the motor end, and not so much at the other end.

My current plan is to remove the bed and loosen the leadnut block enough that it can move, but not easily. I'll then put the bed back together and run it back and forth a few times, that should let the leadnut block find its' own center. Then, it'll just be a matter of carefully removing the bed, tightening the leadnut block mounting bolts, reassembling the bed, and trying it again. If it still binds after that, at least I'll know that I've got a vertical misalignment problem and not a side to side problem.

[ddmckee54]

Progress has been made, tonight I put the Z carriage back in place. It feels stiffer, before when I pushed on the top of the carriage I could feel it flex - that's not happening now. I even added 15mm to the height of the carriage to compensate for the travel loss caused by the coupler. Here's what it looks like with the new Z carriage and the stiffening plates.

Adding that 15mm in height means that the leadscrew isn't long enough to reach reach the lower bearing anymore. I've got a replacement on order. but it's not due for a couple weeks yet. If by some miracle I get this thing running before then, the lower end can just run wild.

I also took a hard look at the alignment of the X axis leadscrew, both horizontal and vertical. Side to side it looks pretty good, it is DEFINITELY vertically challenged though. From what I can see, it looks like the leadscrew is about 2-3mm too low. With the leadnut block firmly bolted to the bed, I was able to get decent measurements from the top of the bed to the top of the leadscrew, from the top of the bed to the top of the coupler, the leadscrew diameter, and the coupler diameter. After running the numbers, I determined that my 6.17mm thick shim SHOULD have been 4.06mm thick. I'll have to add a stack of washers under the heads of the mounting bolts if they bottom out in the slot before they are able to clamp down. I don't think I've got the extra 2mm of clearance under the clamp that would be required by the thinner shim.

[ddmckee54]

I reprinted the shim for the X axis leadnut block.  I had calculated that I needed about a 4.1mm thick shim.  So I printed a 4mm shim - reasoning that it's a LOT easier to add to the thickness of a solid block than it is to subtract from it.  When I put things back together, sure enough the leadscrew WOULDN'T slip into the coupler.  This time it was hitting on the top of the coupler.  It was close enough that I could force it into the coupler, but then the leadscrew was jammed and it wouldn't turn.  I started looking around for something I could use as a shim.  Since I some old business cards laying around from an earlier attempt at leveling the base, I decided to give one of them a shot.  Dumb-luck strikes again, it was like baby bear's porridge - just right.  The leadscrew slips right into the coupler.  And, when turning the leadscrew by hand, I can't feel any difference in drag between when the leadscrew is in the coupler and when it's not.

I'm ninety-nine and forty-four one hundredths percent sure that brings me to a project milestone - the point where I'm done with the mechanical modifications and start aligning the bed to each of the axis.

[ddmckee54]

Houston, we have a problem.  How can I ensure that the X axis rails are parallel to each other?  Just so we're all reading from the same page, let me refresh your memory of what this thing looks like.

Starting in the lower LH corner we have what I am going to call the west side, because that's the way the machine is actually oriented.  The X axis rails are the longer set of rails running east-west, with the Y axis being the shorter set of rails that run north-south.  Keep in mind that the gantry is fixed and the bed moves east and west along the X axis,  The spindle moves north and south along the Y axis rails.

The magenta colored objects that are 50mm from each corner of the frame are the standoffs that hold the frame about 6mm off the base.  Those standoffs are there, because there's a lump in the base.  As near as I can tell, using the edge of a carpenter's square for a straight edge, the east, north, and west edges of the base are flat.  The lump is about 0.008"-0.010" thick, and is centered about 100mm from the south edge of the base, and about 1/2 of the length of the machine from the west end.  Except on the south side, I know those standoffs are in areas that are flat.  The 6mm gap should allow the machine frame to bridge the lump, so the top of the frame should be flat to the east, west, and north sides of the base.  So hopefully, this will allow me to ignore the lump.

So here M'Lords, is my clever plan, at least for the X axis alignment:
1 - I'm going to level the east, west, and north edges of the base.  I've got a precision level, it's not a great precision level, but it's got to be better than a carpenters level.  I've got some leveling feet on order that should make that job a little easer.
2 - After the base is level, I'm going to level the frame to the base.  I'll level it both north-south, and east-west, that'll ensure there's no twist in the frame.  I'm hoping it will already BE level, but... Hope for the best and plan for the worst.  If the frame isn't level, fixing that will involve shimming it level.  Since everything else is somehow related to those side frames, getting them true to the world will make life easier for Future Don.  I got some 5/16" thick float glass that is used to hone wood working tools "scary sharp", this and my 1-2-3 blocks should allow me to bridge over the bed and check that the frames are level - both north-south and east-west.  JBWorxStudio uses the float glass to tram in the spindle of his CNC router, it should work for this too.
3 - Next will be checking that the rails are level, this will tell me if the vertical centerline of the rails are parallel to the top of the frame.  I'm REALLY hoping that the rails will be level to the frame, since the mounting bolts for the rails use the 2 side slots in the 2040 side frame extrusions.  There may be a little wiggle room there, but not a whole lot of it.
4 - Next on the hit parade will be checking the bed,  The bed should be level, it does ride on the X axis rails after all.  But, those linear bearing mounting brackets were fabricated early in this project, before I knew how critical attention to detail REALLY was.  If they aren't level, I'll probably have to slot the mounting holes for now, and make new brackets when I get this thing operational.  I also need to be sure slots of the bed are perpendicular to the side frames. a 6" square fill do for now.

Once I've got the bed level, I can start the process of getting the Y axis rails aligned.

[ddmckee54]

A couple of days ago I got the leveling feet I ordered, I got them installed and started leveling the base.

Having never used a precision level before, I just plunked it down on the base and started adjusting the leveling feet.  This particular model of level has 2 bubble vials, a large vial on the long axis of the level, and a much smaller vial across the body of the level.  I EVENTUALLY realized that you need to get the bubble centered in the cross via BEFORE you attempt to center the bubble in the main vial.  It makes a BIG difference in how that bubble reacts.    That's why you see the level sitting of a piece of paper in the above photo.

Last night I went around the base several times with the precision level, it's as level as it's going to get. I thought that I had leveled the base of the workbench when I installed it almost 20 years ago, if so - I did a really crappy job of it. The base of the machine is about 400mm x 600mm. from the NW corner to the SE corner of the base there's a 6-8mm difference in length of the adjusting stud. The workbench top is flat, it's just not level.  Eventually I got the base close enough to level that the paper shim was no longer needed to have the cross vial's bubble be centered, I could just set the level directly on the base.

Next I check the to see that the frame is level, and then it'll be on to the X axis rails.

[ddmckee54]

I went around the base leveling feet a couple more times, to get things dialed in. All the while wondering if this was a gigantic waste of tine. The more I dug into it, the wonkier the base was looking.

I thought the bottom side of my base was flat, but it's actually concave, in both the E-W and the N-S directions. The bottom of the sides are fairly flat compared to the center. And tops of the East, South, and West sides are fairly flat. The top of the North side has a noticeable hump in it. The base itself is not a consistent thickness. The West side is 0.2mm thicker on the North side than it is on the South, the East side has a similar taper. The South side is 0.2mm thicker on the East side than it is on the West. The North side is 0.2mm thicker on the East side than it is on the West. Which makes the NE corner 0.4mm thicker than the SW corner.

Just for shits and giggles I got out the float glass plate and my 1-2-3 blocks to check if the side frames were level. N-S they were level, but E-W they were not. That required 3 pieces of paper under the West leveling feet as shims. Tomorrow I cut some shims for under the West frame mounting standoff and fix that problem. From here on, everything will be aligned to the side frames - in some way.

It was my intent all along to have the base sitting flat on the bench, probably on a rubber mat for sound deadening. After I get things aligned: the X axis, the Y axis, and the bed - I plan on putting a 1-2-3 block under each corner of the base and see if any thing changes in the alignment. That'll tell me if I can go back to Plan A, or if I need to tolerate that gap under the base and everything that is going to wind up hiding in there.

[ddmckee54]

Well...

Progress on this thread was slow enough already, but starting tomorrow it'll get even slower.  Tomorrow work on my new garage starts, or at least the demolition of the deck where the new garage will be located starts tomorrow.  It's going to be a busy summer.