If you add the epoxy coating, is it possible to replace the aluminum base plates at some time in the future, if needed?
I don’t think Langmuir has posted any details on how to remove and replace the base plate, it may be as simple as pulling all the screws that holding the base plate in and milling the old base plate out.
I don’t see the epoxy being a problem even if you had to use a right angle grinder to remove it around the plates perimeter and touch up after the new plate is installed.
I made a sacrificial plate out of 12x10x3/4” aluminum plate with 1/4-20 holes on a 1” pattern (65 of them took an hour and a half for the thread milling) and I’m putting countersunk mounting holes to match the 2” base pattern close to the perimeter. I figure it’s easier and cheaper to replace if I screw up. I also made one 7x12 with 55 holes I can stick in the vises and do small flat stuff without taking the vises out. The 7x12 already paid for itself when I forgot to re-zero Z before setting the new tool height and put my chamfer mill half way through it. I need to relocate the e-stop! It’s hard to find it on the screen in a panic and it’s useless way back on the enclosure.
I would be willing to bet that slightly chilling the aluminum plates (ice, dry ice, etc.) might shrink them enough to make them easy enough to pop out.
Fuzzy math says that even if you cool all of it by 50° F from the temperature when you poured it (ambient?) the plate would shrink by .003" in the short side and .006" in the long side (from 10x20 to 9.997x19.994).
If that didn’t work then I’d try going a little caveman with a grinder haha
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While in theory you could replace the plates by removing all the base plate to anchor bolts and prying the base plates free, from a practical sense, it will be a challenge. The base plates have a bow to them, so the anchors that will remain and the concrete around them will have the same bow. Also, the sides are not precisely square to the 2x2 or anchor bolt pattern, so once you get past the bow, there will be a lot of fitting of the plate, then once it fits, transferring the anchor bolt pattern, then use the MR-1 to recreate the 2x2 pattern.
It would be best to consider the baseplates permanent and treat them as such.
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My assumption was that the uninstall would be a nightmare. In retrospect, I now wish I had filled the base plate screw wholes with expoxy before surfacing.
I used the wrong bolts for my base plate causing it to sit lower than it should. I caught the mistake before the epoxy pour. Getting the plates off the cured concrete was difficult but possible. You can use the anchors to push against and the threads on the plates to attach to.
I flooded the area under the plates with 1/8" of epoxy for a flat surface. The plates are bowed. However, there is enough play in the plates and anchors that reattaching them with 3/4" bolts rather than 5/8" was no issue. The bolts force the plates flat. The bolt pattern and depth may be specific to these plates though.
The benefit of my mistake is I now have removable base plates.
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Both of my plates were bowed and in the best orientation (in which the 2" grid pattern was only off by 0.030") one plate was bowed up and the other down. The seam between the two plates is a V. This seems to fairly common from look at build pics where you can see cement infiltration. The plate seemed to be moved around at the end from the saw cut and I spent a fair amount of time trying to stone it down so the plates fit up better.
I ended up taking off a whopping 0.079" to fully clean up the surface.
“Not difficult” may be an under estimation. The cement on the bottom of my plates was very well attached. also the rough edge around the plates didn’t help. Having some sort of pulley or lift to pull on the plates may have made it easier, but I didn’t have access to those tools.
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Would you be willing to share pics of what the pocket looks like?
Langmuir’s words not mine.
It was said earlier Langmuir hasn’t said anything or much about it. And I was just sharing as I had the same question, and Langmuir did speak on it—albeit loosely.
When you run out of base plate wouldn’t be easier to flush the plate with the epoxy and add a new - say 3/8" plate with aligned holes, Remove the existing cap screws and install new/longer ones with counter sunk holes like the existing. Yeah, you lose 3/8" of Z distance, but me thinking trying to pry out the old plate could be a nightmare,
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@Kozmonot Absolutely. I just wanted to make it clear if someone saw that message from LS they should be prepared to put in work!
@safety3rd I flooded the space under the plate with epoxy so I have no pictures of what it looked like originally. I can say it looked like the surface of the moon. Lots of craters and voids near the middle with about 1 - 2" in from the edges looking better. I tapped the chip tray for what seemed like an hour to get it as consolidated as possible as well.
@fma.pe.aia After removing all the screws, I was able to break the plate free from the concrete by putting a metal stud through the plate which fit inside the cement anchor. I had a spare 1/4" steel plate with slots cut into it that matched the threaded hole spacing of the base plate. I covered the metal stud with the plate and screwed into the base plate with 1/4 - 20 x 1 1/2" bolts. Washers were used to take up any slack.
When I drove the bolts in it forced the steel plate against the stud and drew the base plate upward. I did that around the 4 corners and through the middle of the first base plate. After that, I was able to attach a couple of bolts and pull up to remove it. The other plate was quite a bit easier as I could get a screwdriver under it to pry. I only needed to used the previous method on the outside edge.
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