MadModder

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.

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.

But I find ChatGPT very goodat answering the 'How do I do . . .  and it digs me out of holes!

I've actually thought about starting a new thread about if there are any positive uses for AI. I have used free version of ChatGPT, and in my case, it's a valuable tool - for example, when I'm searching something on the net, and don't necessarily know what terms to use (as a non-english bugger), it can provide context to take the search further.

Yes, I've used it quite a lot on Blender and Linux issues, but sometimes, it spews things like "I'll provide laser sharp solution to your problems". At one time I told it to not overly elaborate(if that's the correct term) - just stay on the subject, and behave like the machine that you are - no emotional hooks. 

 

 

   

Russell, I would really have liked to become proficient in FreeCAD.

I should say to be fair, it didn't crash often. I think I lost some work one time, but at a bad time in terms of overall frustration in trying to achieve a particular goal. And certainly, running old SketchUPs in WINE (a Windows-like program environment for Linux) occasionally crash, too.

If I'd ever found a path in FreeCAD, no matter how difficult, to achieve that flywheel shape, I would have stuck with it. Because I would then have then thought I'd find quicker and easier ways to do that with practice.

At one point in trying to taper an elliptical sectioned spoke, and then fillet that into the flywheel rim I reached a dead end.

It seemed to me that a possible solution was not to do that in the round, but split the spoke lengthwise -- as if making a half-pattern, before tapering it. But when I tried that, the taper was applied vertically as well as width wise, lifting the flat face, which I didn't want.

I kept running into these sorts of problems. I think they are due to functions (like taper) being pre-defined, rather than achieved through applying primitives -- as you do in SketchUP. In the latter, it's easy, just draw a straight elliptical sectioned spoke, rotate to one end, and then scale it's section with grab handles. Which you can do either uniformly or in one direction only, depending on which handle you grab.

In FreeCAD, you often have to fill in numeric specifications and preferences for an action before you actually do it. If there isn't a slot to change some spec that you need, you're out of luck.

Manipulating SketchUP objects is more analogous to manipulating physical objects made of clay. You form or deform them with on-screen tools, then afterwards set the amount of deformation more exactly by typing in a number.

I still regret not being able to use FreeCAD -- it bothers me not to succeed with something I set out to do, and I don't really want to be dependent on just a single old CAD system.

Quote from: vtsteam on March 26, 2026, 04:26:55 PM

I've tried to learn other 3D CADs and I find them really difficult/clumsy (for me). Maybe it's just the way my mind works.

Do you mean apps like Freecad? If so, yes, it's free, but it has rather steep learning curve - and the fact that it keeps crashing often doesn't exactly help the learning process. That's why I've used it only for converting meshes to another format. 

Yup. I made a really concerted effort to learn it, using a set of video tutorials -- which worked okay. But then when I tried to draw a flywheel with fillets on tapered elliptical sectioned spokes, I found the tutorials were fine for the kinds of shapes each concentrated on, but nothing I tried would allow me to make the shapes I wanted. I gave up after it became too frustrating -- and yes there were also crashes.

I then tried the same thing in SketchUp which doesn't have native filleting ability, and yet surprisingly, I was able to get a very close approximation of what I wanted with primitives, and an add-on I found. It was SO much simpler to draw that, and modify it. One big difference I noticed is that in FreeCad you work in a 2D sketch generally to start with, while in SketchUP, you start right in 3D space and create your drawing.

Anyway, SketchUP to me does mirror the way my mind visualizes things, with basic tools that are easily understood intuitively -- at least for me.