@bertberaht and a handful of us worked on the MultiCAM yesterday adding 6 zoned valves for the vacuum table. Thanks Bert and the team!
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I have a question about screwing down pieces. I know the sign says to not screw objects down, but when working with something like a large live edge slab, I don’t know that I trust the vacuum. Especially if there is cupping and I am working on the first side, the bottom will not yet be flat. I use shims to keep it from rocking, then use blocks of wood screwed into the mdf to hold it in place. Is this no longer allowed? My main use for the multicam is to surface large slabs.
Bring your own MDF spoil board to screw into. the vacuum will hold it down and it can hold your part down.
This was actually something taught when we first got the CNC, but somehow it seems to have been lost in time.
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The primary notice that Bert posted yesterday suggests the following:
I added the numbering for reference. It sounds like his suggestion #2 is probably relevant to the large slab.
BTW, @bertberaht surfaces a lot of large slabs himself. Maybe he will share how he plans to do it …
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Ryan, I also have to shim uneven slab bottoms. Here’s what I will be doing:
Screw my positioning blocks to the edge of pieces of ply, maybe a 1 sqft size or so, push those up snug to the slab, turn the vac on to hold said block plates in place. And mask around block plates as necessary to get good hold power.
Note: if the slab really doesn’t seal to the spoilboard on the uneven side, probably best to mask under it as well so your positioning blocks have plenty of holddown force.
Just a note of explanation to add to Mitch’s second photo.
What is shown is the table with only one zone turned on. That entire zone is masked with a piece of freezer paper except for the shape of the vacuum gauge plate. The gauge is reading 120" of water vacuum.
That compares to the blower producing only 35" of water vacuum AT THE BLOWER when we started all this work. The gauge didn’t register a vacuum on top of the table then.
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Ok, I think that makes sense. It will be hard when working with slabs that are 9+ feet long, but I will find a way to make it work. Thank you for the explanation. Once flipped to the already flattened side the new vacuum should hold perfectly I hope.
I usually have enough curvature along my slabs to have places to apply blocks to resist X axis movement. If your long slab is straight enough down the side to not allow block plates to apply lengthwise force, two options are:
- Drive a screw in from the push block far enough that the point will dig enough to resist slab movement
- Essentially elevate the slab on a “bed of nails” (or screws) so that friction will resist movement. I’ve even done this at times with differing screws lengths to level a warped slab in lieu of shims.
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Heard, I will find a way to work within the new rules to not screw things into the spoilboard. Hopefully it goes more than a week before someone cuts 1/2 too deep by not setting max depth so your hard work and the work of the volunteers isn’t destroyed as quickly as usual.
Can we have some kind of enforcement of rules where somoene who badly damages the spoilboard is forced to retest out and on a second infraction take the class again and buy a new mdf and level it? We are too easy on violations.
I know there will be a learning curve and we are working against the impressive force of Old Habits. Can look at Maker repercussions after the newness is gone. Maybe most deep scarring will be limited to a few zones and not the entire table … or at least one can hope!
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I’d rather whoever damages the spoilboard fill their hole or replace the panel and resurface it.
Mitch, we plan to make a series of short “How To” videos and patching a hole is one we will cover.
Natcha and I also resurfaced the surface block that had a lot of damage from tooling, I mic’d the average thickness and set the thickness on the machine. If you use the surface block please make sure you touch off from the center and make sure you are pressing “0”. The surface block should be accurate within ±0.001"
I applied Velcro so the surface block doesn’t fall off during a job, if it peels off let me know and I’ll probably make a cradle for it.
Natcha is also working on an aluminum laser mount so the laser doesn’t get misaligned.
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And here are the videos!
Here is the update on the recent changes to the Multicam. If you are a user, this is a must watch to understand changes to the spoilboards and hold down. https://youtu.be/o-sNPIZbaK8
A second video detailing a couple other alternative hold down options can be found at https://youtu.be/uV3thBJgTx0 .
A huge thank you to Bert for leadership on this important issue!
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I temporarily took the first gate (section1?) off the vacuum table and bypassed it as it was stuck closed and I could not get the metal rod to hook in to pull it open.
I placed the gate in the maintenance drawer.
Thanks. I am going to have to put travel limits on the valve stems to avoid this happening in the future. In general, I like the valve design, but the “gate to stem” connection could be better. On my “to do” list for today.
Thank you guys so much!! I know this was a much needed improvement.
Chris, I took the valve body you removed and broke it open to see what kind of connection existed between slide gate and shaft. In a word, poor! I used JB weld epoxy to reinforce the joint and installed a stop block to the shaft so it will be stopped before the maximum allowable travel … all of which should help. Should. I made the same changes on all 6 valves. We’ll see how it works.
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