Hi, anyone flattening cnc slabs using the cnc I’m looking into that as I don’t have a jointer/planer yet ,and the only thing that’s troubling me is the high spots.
It’s a lot of machining time to get those.
does anybody have any tips on determining those high spots areas.Thanks.
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Hey. I do it all the time. I have a jointer and a planer but the CNC is so much easier. I just set it up once and go have a tea. Come back to a nice flat piece of wood. You don’t need to stand then and continue to adjust your depth of cut for each pass.
You can do the top of your material and the. Use the planer for the other side. Or if you don’t have one at all. Do one side. Flip it.over and do the other.
Some tips. Zero your machine from the waste board not from the material surface. That way you can choose your final Thickness and not have to measure each time.
Try to level your material on the machine. So if the board rocks, wedge some shims under the material or what I use is hot glue. That way the material is supported and level-ish/ won’t move around.
As for speeds and feeds. I run at 18k 100ipm as for depth of cut it dependant on what you have for a surfacing bit.
Hope this helps.
Happy machining.
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I’ve done it a few times with good results. You have to develop a good method to hold it still and use shims if necessary to keep it from rocking on the table. Find the high spot and use that for your zero reference point. Only take minimal cuts till you get the top side flat, then flip it over and do the other side. I use a 2-1/2” three wing spoilboard fly cutter. Again, clamping methods vary on slabs and sometimes requires some creative ingenuity to get it stationary to safely machine.
Hope that helps.
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It’s a good idea to zero from bed that I didn’t think of before, how do you find your high spot?
You don’t really need to know the exact start depth. Have your machine start cutting above your material and let it air cut down. Set your start depth above your piece and let it air cut until it starts taking material. Not saying start it 4 inches above but .125 wouldn’t be to bad for extra cycle time and it would take the guess work out of things for you.
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Thanks for your help.
When I do slabs on mine, I just turn on the spindle and drive it around with my keyboard to get the high spots started/found. It would depend on the bit you are using, but I take like 1/4" passes with a pretty dull amana 45526 to get the high spots down a bit and then let the program go from there with lighter passes.
For hold downs I use my biscuit joiner and cut a few slots on top of each other so i can fit a clamp in each end. i’m using some 4" long clamp that are made for a cheap t track and they can get in there under the top of the top board so I can mill all the way past. You could make something out of wood for this pretty easily.
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That sounds interesting. Thanks.
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I’ve done a few and the advice given is spot on. Jay hates has a few videos showing flattening and they are really helpful. The speeds and feeds are dependent as they are for most things. I usually just do as previously mentioned and drive my cutter around with the remote (game controller). I have flattened up to 250ipm. But your mileage may differ.
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Do it by hand to get close if you are in a hurry, then follow the above advice, folks here are quite knowledgeable and honest.
I mean literally by hand if you are an owner of a large plane. Or rather, use a router setup that you create similar to the pics attached. A large “indexable” router “head” that holds a few square carbides is a good investment. $200 of router bit, aka shell mill, will cut your time down dramatically.
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Wow nice setup, I’ve seen people use this kind of setup with the router. How do you do about different thicknesses of the wood, do the adjustments in the router suffice ?
Just a plunge router and shims. I’ll add a pic of the “carriage” and the router head I use by hand and on the CNC when I’m in the shop later today.
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I also do a lot of slab flattening using my CNC, as mention by someone else, i also drive the router manually using the jogging keys to find and focus on the high spots.
Once I have found and removed the majority of the high spots i then let the software run a tool path to finish it off.
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Thanks. I did some cuts and still getting some burn marks in some areas. I also had to re tram the spindle. how do you deal with the knots do you machine them as well ?
Burn through them. But that’s me. I check for metal then game on.
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Don’t forget to scan the slab with a metal detector. Never know what is in a slab. Hate to mill thru something with a expensive fly cutter. I use a 2" cutter with replaceable carbide cutters inserts.
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