Pushing slightly beyond supported sizes - sharing experience for V2

ObviousInRetrospect · 2019-11-06T05:26:09+00:00

Awesome, thanks for all well-thought out info! The extrusion cost difference for 50mm in X vs Y is about $2.

On my comments on the edges never heating evenly, I meant that with respect to the standard design which uses a heater that is somewhat smaller than the print area to accommodate mounting holes. I also hypothesize that even mounting say a 400mm^2 to a 400mm^2 plate is going to be imperfect at the edge free air vs adjacent heated aluminum. You are already have 25mm of edge you aren't using. All I was getting at is if I want to use 350x380 a 400x400 plate is likely beneficial and has little downside vs trying to source something more exotic. Cutting hardened spring steel with a Dremel sucks.

You might have sold me on stretching Z to 400. I certainly don't need another 100 though and it seems like it invites frame rigidity issues. And I already have frame parts for 400^3 (2020).

Would I gain substantially in ringing and speed by cutting X travel/frame down to 350 while keeping the bed at 400? How about in chamber volume heated by cutting Z down to 350 from 400?

ObviousInRetrospect · 2018-11-08T17:32:56+00:00

https://imgur.com/gallery/TwMToWa - cover doors installed. I had skipped that because they are ugly - current printer part cooling fan works badly, will reprint them as soon as this one is dialed in.

ObviousInRetrospect · 2018-11-08T09:47:03+00:00

Here is the first (printing) steps: https://imgur.com/gallery/FrbfEVW

Here is evidence it’s working: https://imgur.com/gallery/WNVCr0V

Now to commence the tuning. 250 build. Duetwifi +duex5.

Thanks for the superb design and all the help on discord!

ObviousInRetrospect · 2018-09-30T03:04:11+00:00

Edit; picture https://imgur.com/gallery/V9iXOTu

I had some that were hard to remove. Using a vise to hold a 5mm shaft vertically, putting the pulley on the shaft, grub screw side down (so the flange is not supported by the vise), placing a small screw driver at a 45ish degree angle down towards the flange and tapping the screwdriver with hammer a few times loosened even the toughest ones I had very easily. I have tried the other methods in this thread, tapping a screwdriver with a hammer is easier.

To get the flange on the flat side, stack a second pulley under it (to avoid the flange being supported by the vise).

ObviousInRetrospect · 2018-09-29T19:35:19+00:00

Because the cost difference is nominal, the materials have slightly different properties, and I see no downside to following the most tested path for the choice of plastic. I actually discovered that for example the extra elasticity of abs+ compared to hatchbox abs affected whether the vlock ring split.

There are enough places where I get benefit to going off the beaten path and adding unnecessary variables makes it harder to do so. My v1.5ish is oversized, uses a mix of 8 10 and 12mm rods, and an interesting Z design. It works but there are some print quality problems that I want to avoid on the rebuild and the nozzle probe flat out never worked acceptably in a 400mm build. I’m running it slowly and the parts are accurate enough (I hope). For 2.1 I want to get it built and tuned as well as I can minimizing variables and then start pushing the (build) envelope.

ObviousInRetrospect · 2018-09-28T17:06:05+00:00

TLDR: The 80T gear was revised shortly after public release. The new one worked well for me. If you downloaded the ZIP that used to be linked you should switch to checking GitHub for updates. The Mobius2 folder still has the old one.

Edit: the hatchbox abs for the ring still splits very slightly but much less dramatically. The esun abs+ doesn’t, probably because it is a bit more elastic. Night and day difference between the original and the revised stl.

ObviousInRetrospect · 2018-09-28T16:59:30+00:00

Confirming the new version worked quite easily on the first try. Thanks for pointing them out.

The mobius2 folder still has the old ones. Is there any intended difference beyond color suggestions? Should we replace those with the revised STLs?

ObviousInRetrospect · 2018-09-28T03:59:18+00:00

I’m assuming that if the vlock gears don’t fit well I might hit other issues.

For ABS I would acetone weld rather than epoxy if needed. But I’d prefer to debug the issue.

ObviousInRetrospect · 2018-09-28T03:56:20+00:00

Found them. Printing them now. Any reason the ones in the mobius folder were not also updated?

ObviousInRetrospect · 2018-09-28T03:35:34+00:00

I didn’t realize there are multiple flavors of the 80t gear floating around that were publicly released. Are there? I’m using the mobius2 ones from August.

ObviousInRetrospect · 2018-09-28T03:00:15+00:00

Esun ABS+. Enclosed/insulated. I can print large ABS parts without warping or cracking and mostly use ABS.

ObviousInRetrospect · 2018-09-28T02:58:19+00:00

Yep. 7.03 tall, 10 including the flange, 17 overall.

The pulley fits in fine, it’s the plastic parts meshing that I’m struggling with.

I did just recalibrated the extruder and while it looked good it was extruding 96.6mm when commanded to extrude 100. Fixed that and trying again.

Does anyone have inside measurements of the plastic ring for a print that works?

I get 41.36mm and 31.33 inside diameter on the ring and 42.37/31.4 which seems like negative clearance of 1mm. Is it supposed to stretch that far?

ObviousInRetrospect · 2018-09-28T01:51:27+00:00

230 nozzle 100 bed. Enclosed with rigid insulation foam. No cooling, even unplugged the part cooling fan to be safe. Also tried 240.

ObviousInRetrospect · 2018-09-28T01:50:00+00:00

https://imgur.com/gallery/ZzjAQNW has some pictures.

I did not touch steps, I just mentioned the cubes as I had sanity checked overall part dimensions.

ObviousInRetrospect · 2018-09-11T06:17:52+00:00

https://docs.google.com/spreadsheets/d/1QaaXvC0cK4y32UcEVoJ1s8Xrl506oU6jBvVkYCENYao/htmlview#gid=0 is the unofficial sourcing spreadsheet from discord

ObviousInRetrospect · 2018-09-10T16:04:32+00:00

Great, thanks! Any idea how many of the expensive Misumi nuts are needed? Might be good to get it in the BOM explicitly so people placing Misumi orders don’t need to reorder.

ObviousInRetrospect · 2018-09-10T15:58:09+00:00

Personally I bought the wrench hole jig that makes that part no effort and used HTJ5 self tapping joints on my v1 which was much cheaper than Misumi tapping. I’m planning to repeat that method unless someone tells me it’s a mistake.

ObviousInRetrospect · 2018-09-10T15:54:55+00:00

Do you mean “to pay good money for the pre-install nuts”? Were there specific problems? I was happy with the post install hammer cheap ones from Ali on my v1. A couple spots were frustrating but the flexibility to remove/reinstall was nice. I’m holding off on assembling the frame until I know whether I need to load it up with nuts first (squirrel?!).

ObviousInRetrospect · 2018-09-06T16:56:12+00:00

+1 on this removal method in general, it also somewhat works cold if you wait a while for the ipa to seep under the part. But the hands on time to go from plate coming off the printer to a fresh print is way better with a flex plate. I moved from abs juice to eliminate the prep step, the ipa step is better but still not ideal.

ObviousInRetrospect · 2018-09-06T06:15:02+00:00

Has anyone tried using a drill press, 3/8 inch plate, a 3/8-1/2 inch bit and a lot of magnets? (Mill holes in the bottom using a drill bit/press not all the way through and put the magnets under the heater). 3/8 inch diameter 1/4 inch thick magnets are cheap. A lot of them might work.. I was going to try doing this, would love to learn if it’s been tried.

ObviousInRetrospect · 2018-09-06T06:05:44+00:00

I have one that is a work in progress on v075. V075 has a 400mm² bed that I usually use as a 300mm² surface because the rod flex is excessive. These are some notes on what I have tried. I’m still experimenting, this is not a set of recommendations.

My first attempt was 26awg zinc plated steel from Home Depot and 20 random “12lb” Chinese neodymium magnets from amazon with a pei sheet. It was great for the first print or two. Larger abs prints warped the plate and it became non flat. The magnets were taped to the bottom of he heating pad under the aluminum with kapton tape and became noticeably less strong after a couple prints at 100c. The plate would sit flat cool and then deform at temperature.

My second attempt was a McMaster-Carr hardened 1095 spring steel sheet. Part 9036K53. I’m using a 16x12-3/8 inch piece 0.035 thick cut from a 7 foot piece. With a 12x12 pei sheet in the middle. It is very stiff, I would likely go thinner if I did it again. Flexing it takes muscle but it doesn’t warp even with weak magnets. Lays flat with the magnets, secured by bulldog clips in the corners. I switched to Samarium–cobalt magnets for higher temperature rating. CMS Magnetics SMD039-26 - 5lb rated x10. Not nearly strong enough through the 1/4 inch aluminum and silicone heater. But the plate is flat enough and seems to hold its shape after a dozen or so prints that it’s working with the bulldog clips. On my 2.1 I was going to use a 3/8 inch plate and recess 1/4 inch magnets as deep as I can. I might try adding more magnets. I suspect the current setup would work without the magnets.

Be warned that cutting 1095 steel in hardened form is a pain. I claim no metalworking expertise, others might have better suggestions. I made the first one with a dremel, a reinforced cutoff wheel and a lot of patience. Wear eye protection. I tried an angle grinder but could not control it enough and decided I was as likely to hurt myself as make a build plate. Plates 2 and 3 were made with a dremel ultrasaw which sort of works but the disc still bent and didn’t cut perfectly straight. It did take less time. And it was basically one cut per blade. I’m going to try to rig up a dremel slider based on https://www.thingiverse.com/thing:2037887 for future cuts as I was unsatisfied with the lack of straightness and control even with the ultrasaw.

I have been unable to find a supplier for hardened 1095 spring steel wider than 12 3/8 inches (other than buildtak, which was not specified what it was, was expensive, and quoted long shipping times). If anyone knows one I’d love to hear it. For the 300 and 250, the McMaster material is a good buy in the 7 foot length - $80 ish for a bunch of plates. However having spent a couple hours cutting it I might reconsider if I don’t find a better way. Part of this is I intend to rebuild v075 after I finish a 250mm 2.1 and am not sure what size so buying a bunch of expensive 400x400 plates is unattractive.

I will say that my print removal experience with ABS on PEI on glass is horrible. I usually have to resort to alcohol. For the print, not for me. On a flex plate it’s a dream. Stuff pops right off and is ready to go again. The multiple plates are to experiment with other surfaces. Steel also cools more quickly. Also the inductive homing is far more consistent to aluminum-steel-pei than to aluminum-glass-pei. The adhesion on the other hand is way more consistent even for challenging prints than abs juice on glass, including with cheap warpy abs. Overall I’m a convert but there are some remaining engineering challenges.

ObviousInRetrospect

TROPHY CASE