It's new to me

[ddmckee54]

This time I remembered to export the new CNC assembly as a JPG file.

The magenta colored bits are the parts that will be 3D printed.  I added all the spacers to the 3D model that will be used to bolt the main frame to the base, and the spacers that will turn the two Y extrusions into a sort of truss.  Coincidently, all those spacers also got printed today, and the center-points for the holes in the base got laid out.  I've got to get the holes drilled in the X and Y rails so I can verify that the locations are correct before I drill the base.

[ddmckee54]

Well...  It's one step forward and two steps back time again.  I got the machine mostly disassembled, the Y rail extrusions have been removed, marked, drilled, and bolted back together into a single truss.  (Had to run out and get some longer bolts, the bolts I had were too short, or too long.)  I also added the grease zerks to the Y axis linear bearings, two straight zerks on the two top bearing blocks, and two 90 degree zerks on the bottom blocks to make greasing them easier. 

I had taken one of the X axis rails off and as long as I has the kit of zerks fittings out I figured that I'd add the zerks to those bearing blocks as well.  All of the set screws in the Y axis bearing blocks were black oxide, the set screws in the X axis blocks were SS.   I didn't pay too much attention to that at the time.  Not, until I discovered that the Allen wrench that fit the black oxide screws would not fit the SS screws - too big.  That's when I discovered that the black oxide screws were M6 - which I knew, but the SS screws were M5.  I ain't got no stinkin' M5 grease zerks, M6, M8, M10, 1/8" BSP, and 1/4" BSP I've got - but no M5's.  They are now on order.  The X rail that is out has been marked and drilled, tomorrow I'll remove the other rail and get it marked and drilled too.  I center punched the mounting hole location that was closest to the edge of the base, when I used a transfer punch to mark the other mounting hole in that rail it was about 10mm off from my layout.  I remember that when I added the mounting holes to the base, one of the mounting holes at the RH end of the machine was 10mm off - so I corrected it on the base.  I then made the 2D drawing of the base that I used to lay out the mounting hole locations on the base.  I think I moved the wrong hole in the model, so that's why the RH mounting hole locations were wrong.  Good thing I decided to do a sanity check before drilling the holes in the base.

[ddmckee54]

Picture time...


This is what things look like now, doesn't look a whole lot different than this one does it?


If you answered no to that question you'd be absolutely right.  But there is one MAJOR difference, the frame is now bolted to the base and living in its' new, and permanent, home.

Next step?  Get the bed mounting brackets designed/fabricated, and get the bed mounted to the X axis bearing blocks.  If you look closely at the base below the second mounting bolt for the X axis linear rail on the far side you'll see the access hole for greasing the X axis bearing blocks. (There's a similar access hole on the near side that's hidden in the view.)  Once the bed is mounted I can get to work on the X axis lead-nut mount.  I really need to find mt ToDo list and get it updated, this should check off at least a couple more items.

[vtsteam]

Is the base from a table leaf? Just guessing!

I'm kinda interested in the MKS DLC32 that you mentioned earlier. I'm pretty unaware of the current CNC circuitboard stuff going on in the maker world other than a failed attempt I made at implementing a working GRBL Arduino system for my older CNC router/mill.

Luckily in that case I was able to get an old laptop working with LinuxCNC again which does work fine with the mill via ancient parallel cable drive. So I dropped GRBL. But I am always curious about what's going on in low cost CNC driver options in case I want to make a custom specialized tool some day, neither lathe nor mill.

I think I understand how that one is programmed, separately from the mill, and then the program is loaded and run either by thumbdrive or wifi etc. I do have a tiny extremely low end 3D printer that accepts a thumbdrive program and then runs it, so I get the concept.

[ddmckee54]

vtsteam:

The base is a 470x550x30mm piece of laminated phenolic plastic, with a kraft paper core and what, if I'm remembering correctly, were known as canary covers.  On my bathroom scales that chunk weighs in at about 25 lbs.  In the mid to late 70's I was working in a plant that produced them, in the maintenance department.  Every once in a while a sheet would get rejected, this one has about a 0.010-0.015" high spot about 200mm from the LH side, I suspect that was one the reasons for it's rejection.  I'd keep my eyes open for any rejects that I thought might be usable in the future.  Since they were bound for the landfill anyway, I'd get permission from the production supervisor to take them. 

The only ones I wouldn't take were the epoxy/fiberglass sheets, those you can't cut with carbide blades.  You have to use a diamond saw on them and basically grind through them.  At that time, carbide saw blades for home use were EXPENSIVE, a diamond blade was the stuff of dreams.  We had one guy in maintenance whose sole job was to sharpen and repair the carbide saw blades.

[vtsteam]

Wow, that's a pretty impressive piece of phenolic! I remember it used to be used in low cost PC boards, but not in 30mm thickness! What were those boards used for?

[ddmckee54]

My guess would be that it was probably used as an insulator, the stuff machines fairly easily.  I poked the access holes and the counter-bores for the mounting bolts using nothing more complicated than a Forstner bit in the drill press.

The thickest slab I ever saw them press was 11" with a canvas core.  At that thickness things can get a little dicey, so they are very careful about how they do it.  I also saw them try pressing a slab about 8" thick only to have it spit out the side and bind up the press.  The press itself was a big hydraulic cylinder in a pit, we wound up changing the seals after this incident and I'm thinking the ram was 36-42" in diameter.  The 4 studs connecting the cylinder to the top-hat were 8-10" across.  The only thing that dropped the press ram and the heating platens was gravity.  When the laminate shifted it became wedge shaped, that cocked the ram in the seals - so it wouldn't drop.  They attacked that slab with hand chisels, air chisels, sawzalls, I think they even used a chainsaw on it.  That particular type of laminate was designed to laugh at most shock loads - it's used for gears that need to stand up to repeated high shock loads.  They finally got enough clearance between the slab and the studs to wrap a cable around the slab.  Then some brave soul lunatic volunteered to hook a fork lift to the cable and yank the slab out of the press. (I knew him, lunatic fits.)  From the tire marks we had to clean off the floor, it did not give up easily.  Between getting the slab out of the press, and waiting for the new seals, that press was down for the better part of a month.

[Muzzerboy]

Presumably this is Tufnol, usually paper or cloth with phenolic resin. I used them for high voltage insulators and mounting plates for electrical assemblies. Also used for gears. Easy to machine but has a characteristic slightly acrid smell..

I have some 12mm sheet (plate?) and 50mm rod in the workshop somewhere....
https://tufnol.com/materials-and-products/

[vtsteam]

Wow, exciting stuff re. that press incident! 

[ddmckee54]

Tufnol would be similar, but appears to be a UK product.  Almost 50 years ago I worked at https://www.norplex-micarta.com/ in Postville.  At that time the parent company was in Lacrosse, WI, and Postville was definitely NOT the headquarters - let alone global headquarters.  Some of the stuff in the video on the website looks VERY familiar.  At the time I worked there thermoset sheets were the only product, but there were many flavors of those.  May have to do a Google Earth and see what the plant looks like now.

[ddmckee54]

I got the brackets cut to length and the inside corner radius removed. I found out that my method for bolting the frame to the base may NOT have been such a great idea. Not modeling the bed initially was not a wise move, it gave me the false notion that I had plenty of room to play with. I forgot that the bed overhangs the main frame. Those mounting bolts mean I either need to raise the bed 6-8mm to clear them, or I need to swap those bolts with something else, neither of which I planned on doing. Raising the bed would probably be the simplest, but that means my 65mm clearance over the bed drops down to more like 55mm - at least for now anyway.

Or.... Maybe I just notch the ends of the bed extrusion, that might be the simplest/easiest thing to do. I'll have to check that out, we're probably talking about removing a 10x10mm notch from the bottom of both ends of the bed extrusion. I'm not sure, but I think that extrusion is at least 15mm thick, might be 20mm or more. And how often do you need to put a tee-nut in the last 10mm of the slot? I REALLY need to get the bed modelled, so I can see it before I do any slicing and dicing.

[BillTodd]

This stuff?

[ddmckee54]

Bill, that's the stuff.  But I had a reason that I didn't need to model the bed - explained below.

Is there a Meathead of the Month award?  If there is, then I'm nominating myself!

I was down in the shop taking enough measurements to allow me to model the bed.  I found that I've got 5.28mm between the bottom of the bed and the top of the frame.  OK, now how far does the head of the mounting bolt protrude above the bottom of the bed?  I measured the top of the bolt at 11.62mm down from the top of the bed.  A little head-scratching later and I determined that a 5mm deep notch would give me almost 2mm of clearance.  Hokay-fine, now how wide does the notch need to be?  Better make sure the bed is centered first.  Why is there such a LARGE gap on the far side of the bed, how wide is the bed anyway?  Survey says: Bed width - 300mm, space between frame rails - 400mm.  (Insert head smacking Homer Simpson DOH moment here.)  Wade-a-minut-here, why is there only about 10mm of the bed sitting on the mounting bracket?  (Insert another Homer Simpson moment here!)  Some dip-stick forgot that the horizontal leg of the bracket needed to point to the center, not the outside, of the machine. 

I still need to trim a few mm off the vertical leg of the bracket.  But, I can actually gain a couple mm of usable Z height out of this - instead of losing height as I originally feared.

I didn't model the bed because it CAN'T interfere with anything.  Despite my original panic, this turned out to be tempest in a tea pot, a much ado about nothing, a Rosanna Rosannadanna "Nevermind" moment.

[tom osselton]

I?m afraid the ? Meathead Award ? died with Archie Bunker.
https://youtube.com/shorts/h8o-61uvYbw?si=afbKmCy9Org_1DXl

[ddmckee54]

Ah, the Sock'n a Sock and a Shoe'n a Shoe bit, I think about it every time I put on a Sock'n a Shoe and a Sock'n a Shoe.

[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, https://www.ebay.com/itm/157340497226.  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.

[ddmckee54]

I added another 20 or so items to the ToDo list, another 15-20 on top of that and the mechanical part of this build will be mostly over.  Then I'll get to the part I'm more comfortable with, the controls/electrical end of things.

[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.

[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.

[vtsteam]

Don, I try to visualize in your posts what you are describing, but often fail. Even a pencil sketch on a photographed napkin might help me "get it". Otherwise, just in general, sounds like you're making progress, and I'm looking forward to seeing the completed mill! 

[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.  (vtsteam - I'm usually too lazy/busy/forgetful to remember to take pictures.)

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.