[peteeng]

Hi All - Been having fun with holes, bolts patterns, mirrors and assembles. It's like the first fit of a machine. It never goes together quite like you think it should. Then there are the technical hiccups when you use a pattern inside a mirror, twice and the software won't play that game and fails. Plus I was using P2 as a reference model and being old models did a save and saved old models over my new work. So don't open an old model first when using as a reference. Open it after you open the new model so it updates the old model not the other way round... Always learning something. This is mainly because I don't model all the fasteners usually.

But I'm overcoming the issues and it's coming together. A new sub-assembly break down makes life easier. So I'm building and rebuilding the machine virtually just like Fit#1 and Fit#2, I suppose but in the computer. By Fit#3 everything is as smooth as baby oil. Do they really make Baby Oil from Babies? Peter

[peteeng]

Hi All - Good News. I now have a fully functioning Maximus-HD assembly with no conflicts. All the axes work and the subassm's make sense. Now we start the drawing stack in ernest. Peter

[ericks]

Well done mate

[peteeng]

Hi All, Ta Eric - I now have a proper GA and a Bolt BOM. First nearly automatic bolt BOM I've ever done. YEH. I did the atomic BOM then hide all the none bolt items. This consolidated the bolts across the sub assemblies, something that has eluded me for a while. The test BOM went well. Now get some dwgs going and work thru the holes and check all the bolt lengths. Then we can get to R4. Round 4 will be final simulation, costing and adjusting the design to a budget (to be established) Plus need to start thinking about wiring, cable chains and terminals etc. Then Round 5 will be polishing. Get out the Silvo...

I may have to not use configs for bolts into the future as technically every part should have a unique part number. Doing it this way they do not. So this means making a series of bolts of required lengths of different part numbers and using them. I could make it the same PN with a -55 suffix meaning its 55mm long but I try to make PN meaningless to avoid conflicts.

Having been right thru all of this, my only design concern is the closeness of the Z axis bearing plate bearings. That's where it all started. I could put them to the side of the gantry bearings but then it would make the machine very wide. This maybe a bearing quality issue. Something to think about while the dwgs start to pile up.

I also have been adding extra "wholes and accommodations" (as Mr Planck asked for ) to parts where I think extra bits or brackets will be needed as they are opened. Peter

[peteeng]

Hi All- Details and more details. The drawings are starting to stack. Peter

[peteeng]

Hi All Lurkers - Been away for a couple of days doing some sailing trials on a flying trimaran. Not enough wind to fly but sorted a lot of the boat. Back at the coal face. Have sorted all the assembly drawings and corrected a few part names that I used from old projects. Corrected some part/assm links and made more part dwgs. Now the assemblies are correct, I can get serious at a part level. The paper stack gets reviewed, marked up then next cycle gets corrected and reprinted. Use a lot of paper in this process. When there's no more mark ups its done. Thinking about the motor mounts on the gantry. Probably need to make these a bracket so it can be customised for different machines, I'm sure some people are going to want to use N34's or a ballscrew. So will come to that when I get to the gantry parts. Peter

[Zorbit]

Looking good.

I'm frequently surprised to see that people buy a quality ballscrew and then mount the stepper motor on the end using long, spindly stand-offs, seemingly unaware that twist in these will screw up the accuracy when the machine is under load. I look forward to seeing your solutions.

[peteeng]

Hi Zorbit - Good to know your still out there. Yes some standoffs are very spindly. I have not done any simulation on the motor mounts or returns. So this will be put on the to do list. I've just finished fixing a couple of inconsistent dwgs in the assemblies and I think I'm clear to work on the parts seriously. I organise my axes so they are wisywig to the DRO on UCCNC. The laptop will be to the side of the machine on a small ledge so the Y axis will be the transverse axis (the gantry direction) and the X axis will be the long axis, along the table. So the X axis will have a slave A axis. Just thinking ahead... Peter

[Zorbit]

On the subject of "thinking ahead", have you considered making it easier to retro-fit a toolchanger ?

[peteeng]

Hi Zorbit -Haven't been involved in a tool changer before so don't know exactly what's required. At the "Maker" level ATC's would be rare I think. But if you have a bullet point list of pointers I'm happy to see where it goes. Still working on drawings....Peter

[ger21]

and then mount the stepper motor on the end using long, spindly stand-offs, seemingly unaware that twist in these will screw up the accuracy when the machine is under load

Before the arrival of cheap chinese steppers, people used high quality components, then came with real spec sheets and technical info. These would tell you that a motor should be mounted to a solid plate, preferably aluminum if it was running hot, which would act as a heatsink.
A stepper should NEVER be mounted on standoffs.

[peteeng]

Hi All - Beavering at the dwgs. Added them up, about 100 to do and I've established 19. So about 20% in. By established I mean the dwg exists and is linked into its parent in the database. Then it's easy to change and update via the part or the assembly itself. If the part changes the drawing changes. For instance just checked and changed the hole sizes on one of the bearing brackets to allow a little more clearance, the dwg updated automatically. As I'm establishing drawings I'm checking PCD's, hole sizes and alignments. I'm also noting on the dwg what's important in that part.Once the full set is established I can run through them at a detail level. Cheers Peter

[ericks]

Hi All - Beavering at the dwgs. Added them up, about 100 to do and I've established 19. So about 20% in. By established I mean the dwg exists and is linked into its parent in the database. Then it's easy to change and update via the part or the assembly itself. If the part changes the drawing changes. For instance just checked and changed the hole sizes on one of the bearing brackets to allow a little more clearance, the dwg updated automatically. As I'm establishing drawings I'm checking PCD's, hole sizes and alignments. I'm also noting on the dwg what's important in that part.Once the full set is established I can run through them at a detail level. Cheers Peter

Wish i was this well organised!!! Great job

[peteeng]

Hi All & Sundry especially Sundry. Still going on the dwgs. If there's 100 to do just clicked over the 30% mark. I'm only doing dgws for the sheet-metal quote. It will take 2 weeks or so for them to get the quotes back. I'll send them out to 3 companies. While its out for quotes then I'll do the other dwgs so it should be all together by the time the main quotes are in. Then I can put the whole shebang together and figure out how much it should cost then adjust parts to the budget. Cheers Peter

[ericks]

Looking great

[peteeng]

Hi out there - You would think that getting a belt lined up with parts is an easy thing to do with a high powered CAD system? NOT. Once you realise that there are over 10 parts to get right and they are all interbreed, you suddenly find your in a mess. My prior machines used motor and return mounts that were deliberately designed as identical and they had to be set up with the correct gap to the rail. So this issue was a fitting problem not a design problem. On Brevis (prior machine) I tried to design mounts that touched the rail so set up of the offset was automatic. That didn't work out. On Maximus I bent the flange of the mounts outwards so it fays to the rail creating the correct offset. Perfect... makes for an easy fit-up. I then decided to make a spot drilling template so its even easier and in this process found one end was 1.5mm out and the bolt pattern was different at the motor and return ends. So I adjusted the bolt pattern and offset but the belt alignment was still wrong.... going in circles again.. But once I found the magic token it all fell into place and I can get to the next level... So now we have parts that automatically set the belt offset and a spot drilling template that makes life easy for fitting. More hours burned... Back to drawings...Peter

[peteeng]

Standoffs - Hi all... A question about standoffs and mounts came up so I've had a quick look at it since the assembly was open. I simulated the motor mount assm. Its 4mm S304. I put 100kgf on the pulley to see what moves. I have supported this at the bolts so i will have a little more support in reality. The pulley deflects 0.03mm and the mount deflects 0.01mm. I may make the mount 5mm vs 4mm but the motor axle will still deflect 0.02mm. I'll come back to this next drawing round.

I looked at the loading in non-linear and the mounts are slightly strain stiffening. I also did a more accurate run and the pulley deflects 0.041mm and the mount 0.028mm so I'll look at this when I'm looking at the bigger picture next time around. "normal" loads are probably 1/10th of this maybe 30kgf max tool load. Since some parts of the machine stiffness is discussed in N/um this assm would be 25N/um stiffness. The bearings are some 600N/um and the machines target tool stiffness is 10N/um. 1um = 0.001mm Cheers Peter

[peteeng]

Hi All - The stack is getting thicker. Nothing to report, just more and more drawings!! Have rationalised a few dims on the way, also looking at the return pulleys, I think I'll use two bearings. I think a bearing will be cheaper then having the spacer machined & the dims of the spacer worked out to be the same as the bearing!... I'm near finished the gantry parts then the tool plate is the last assembly to break down. Then I can get back to the interesting stuff...Cheers Peter

44 done and I think it will be around 80 to do.

[peteeng]

Good Morning CNCZONE - Completed the sheet metal dwgs. 14 assembly and 38 parts = 52 sheet metal related drawings. Now I check all the holes and fits and can get it quoted. Checking begins. Peter

[peteeng]

Hi All- working through the holes in the parts and checking they all align. But looked at the mounts that I simulated a little earlier, turns out they need to be 5mm thick to take a thread. There's not quite enough room under the top for nuts so threading it is. But 4mm is a bit thin for a 5mm thread. So I've upsized the mounts. All for the better. Peter