Home depot finally got there machine working again and I was able to buy a big piece of wood to use as my bed. I’ve seen a few different method, vacuum suction, holes drilled every X distance to be used to hold clamps (with and without captive nuts in those holes) and even some weirder ideas (horizontal clamps that push against a lip and force the wood down using a slanted edge at the end (I like this idea a lot because it doesn’t involve drilling a million holes!)
I’d like to hear other suggestions and advice on this, I dont plan on cutting anything huge, and my CNC bed is about 24/32 so it wouldnt be ‘to’ bad to drill holes over the whole thing.
Harbor freight has some super cheap f style clamps that have a pinched “nubbin” that keeps them together. If you grind that off, then you can disassble the clamp and put it through the table. I got the idea from a Jay Bates workbench video, but I’m too lazy to search for it now.
On my low rider table, it’s harder to do through clamps, so I just put 1" #6 screws in places that won’t get cut. That works for things that you’re cutting out. I’ve even used cad to mark where in the piece it’s safe to put screws and have the CNC go down 2mm or so in those places. That’s really useful if I want to hold the middle of a cutout piece down.
If you’re engraving something that you don’t want to put screws in, you can do clamps or you can put a longer piece of wood on the edge (like a ramp) and put a screw in the middle of the ramp to hold it down. If you do a bunch of through cuts, you’ll do much more damage than a few screws.
Like Ryan said, I wouldn’t do the whole grid thing (unless you think that’s fun, which I would understand). At a maximum, I would make holes a few inches apart on the x=0 axis, y=0 axis and x=y axis. That would work for every project I’ve done.
Hmmm. I like the idea of not having to drill all of the holes right now haha.
no harbor freight where I live sadly, in fact almost no ‘hobby supply’ stores at all so I’m forced to use home depot and mom and pop hardware stores (Along with the internet) to find everything I need.
I’m looking at designing some 3d printed clamps I can just drill into the bed where/when I need them.
These look a little different than mine. Specifically, I was going to point out where the pinch hold part was, and these have some sort of pin instead. Mine just have that end pinched to make it a bit wider, which is what I attacked with a dremel and some patience to get them to come apart.
This is the video that I saw about it (but he decides to cut the head off instead of disable the tail):
A couple of 1/8" or 1/4" holes in the spoil board can be used to insert dowel pins. Then a couple of holes in the stock in places that will not be machined will prevent any X and or Y movement. A simple 3D printed jig can be printed for alignment. You still need a Z clamp but there are lots of solutions out there.
made some progress today (got the right bit to actually mill something now) but I’m still having issues getting the thing to be level, I thought it was pretty level but it seems there is a ‘bump’ somewhere in the middle. Trying to figure out why as there are support beams going a crossed the whole way and there all aligned to the wood above it and to the side of it so the only way it would be bumped there is if all of the wood is bowed out there. So I’m trying to figure out the best way to A) figure out what the actual issue is, and B) level it out. Its only maybe a meter or two off, but its enough to cause issues for sure in that one spot.
Take a half millimeter off your spoilboard with the router. That will flatten out your bump. Wood’s not flat, that’s just how it is. Might take a couple passes, might only take one. Find your high spot with a straight edge and set that as your z zero. I drew a square the same size as my spoil board and imported that into estlcam. Selected the square and make a pocket with a peel routing path at a .5mm depth of cut. Set the x y zero to the center of the board.
My board is 20" by 18.5" and it took an hour and a half with a quarter inch end mill. Forget what the stepover was though.
The only working bit I have its a 1/4" bit, so I’ll be using that (till the ones I’ve order from this very webpage arrive later this week!) I setup a gcode for it and its ready to go tomorrow when I feel like people wont get mad for me running a loud drill for 2+ hours, lol.
I actually use glue for a lot of things. When I cut things like Quadcopter frames or 3D skeleton puzzles I hate having to leave tabs to hold pieces in place. They can be a real pain to leave and I always seem to mess up my Z and either accidentally cut through the tabs or leave them so tall they’re a pain to get pieces loose.
I’ve also had issues with finding flat ply at my local stores…it’s almost all warped to some extent and won’t lay flat. I’ve also had problems with my work lifting up off the table if I only screw or clamp it down.
So what I’ve been doing lately is I cover the bottom of my workpiece with 2" wide strips of blue painters tape (or masking tape, but I find painters tape to be a little nicer to work with and not that much more expensive.) and then putting a matching layer down on my spoil board. Then I just glue the two layers of tape together. For smaller items CA glue on one side and a spritz of kicker on the other works great - glues instantly and doesn’t come loose. For larger pieces I’ve been using 3M industrial strength spray on contact adhesive. Two coats on each side - let it get tacky for a minute or two…then stick it down.
I could probably get by with a single coat of spray glue…but wanted to be safe. It works great everything stays in place - even little parts with no tabs! But it all comes up easily when I’m done even though it’s also strong enough to hold even the crazy warped ply I find locally flat.
And with my work finally held that well and flat I’ve finally got my Z consistent enough that I can actually cut through just the top layer of tape if I choose to now.
Oh, one other little benefit…my cuts come out a little cleaner since the tape helps keep this cheap ply from splintering as much.
The only downsides are it’s single use so does cost a bit…but a roll of tape and can of spray glue have lasted me through about 3 4x8 sheets of material. And if you do cut through the tape then it can leave tape residue on your bit and the edge of your cut.
(and yes, carpet tape works too…but…it’s more expensive, is harder to remove, and if you cut through it makes a much bigger mess on your cut and bit than the painters tape does. )
Well, I tried to level out the bed today, and the only bit I had that worked got ate up, I don’t think it was because of anything I was doing wrong, but that it was a crappy quality bit and couldnt take being used that long (it was ground flat on the bottom when I stopped it) more bits are on the way so I guess I have to wait till those arrive.