In the process of trying to buy a CNC. I am a total newbie other than being pretty proficient in Sketchup and they’re extensions. As far as actually running a machine, I have no clue.
I build custom cabinetry full-time - mostly living room, fireplace, bedroom built-ins. Not kitchens. I go through a lot of sheet goods.
I am looking for a CNC to process all of my sheet goods and possibly build one piece MDF doors (but mostly for processing sheet goods)
In many of my cabinet maker forums, people say don’t waste your time with anything that doesn’t have a full vacuum table and ATC. The problem is, machines that come with that standard are around $60,000 and up and need a forklift to unload for delivery. I only plan to be doing this a few more years so don’t want to invest that much into this. I realize that people add these features to Avid setups but it seems to me that that is quite involved.
My questions are:
1. If I’m just cutting out rectangles, with shelf pins and holes for hinge plates and drawer slides, also possibly some light jointery or holes for Lamello fittings, do I really need ATC? Is all of that potentially done with the same bit?
If not, how easy is it to change a bit? Looking for this to be as hands off as possible
2. If I don’t have a vacuum table, what have you guys found is the best way to attach a 4x8 sheet of plywood? Keep in mind, none of them are completely flat and often have the slightest bow so whatever method i use would have to flatten that out. Again, trying to speed things up for myself, so I don’t want it to be too much work to pull a sheet off and get a new one ready
Even when “just” machining sheet goods, consider… my ATC buildout has multiple types of 1/4 router bits, multiple chamfer bits, and a drill or two. And a laser. The last big sheet goods project I did used a minimum of two bits - a drill for all the screw/bolt holes, and a 1/4" bit for the profiles.
For your case, imagine you need a compression bit for outlines, a straight or down cutting bit for pockets (euro hinges), a drill or center-cutting endmill sized for shelf pins, and possibly a chamfer bit to clean up some of the edges and/or “write” text or icons as needed.
Even for such a small list of tooling, an ATC means non-stop machining, and repeatability on bit changes.
As for a vacuum table, you can build one, or have you looked at the composite nailers? On my CNC I put a 4’ wide table on a 5’ wide machine so I can just clamp along the edges.
I just got a bunch of plywood cabinets/drawers! I have a 4’x8’ ATC Avid, no vacuum table. I’ll have a video about it in a week or so.
Personally, if I was doing sheet goods all the time I would really want a vacuum table. The plastic pneumatic nailer would work well too, but it requires a lot more setup and removal for each job.
An ATC is really really handy for consistency and swapping between bits. I had to remove my rack to cut a full 8’ sheet, so I had to “manually” swap bits, but it was just a quick push of a button. I’d recommend a 10’ table so you have room for the rack.
I have processed a lot of sheet goods for cabinets and similar projects on my Avid (Pro 60 x 120) with 3 HP non-ATC spindle.
Shortly after doing a lot of sheet work I added a self built vacuum table covering a 4’x8’ area. This dramatically increased my efficiency over any other hold down method for sheets. The vacuum is much like the hurricane vacuum solution available. Its s budget friendly but be aware these blowers are LOUD!!!
You sacrifice other hold down mechanisms when you have a vacuum table – you need to keep the vacuum surface (usually MDF) flat and not punctured. This means you can’t use dog holes, t-track, or other common solutions within the vacuum surface area. Also, if you cut your sheets into a lot of parts, particularly smaller parts, you will still need to employ some level of tabs to keep those parts in place.
I believe the ideal is to have the CNC larger than the sheets you need to cover. That way you can have some non-vacuum holds and a vacuum section of the table large enough to hold your full sheets. I my case, 60 x 120 is a bit small because I have a rotary. Without the rotary, this would have lots of room for both vacuum and non-vacuum sections.
Tool changes aren’t difficult, but they interrupt your flow and decrease your efficiency. Since I don’t have an ATC (yet… will very soon), I found I often used sub-optional bits for operations so I didn’t have to do a tool change. For example
Cutting dados for 3/4" material using a 1/4" compression bit. Took much longer than using a 3/4" downcut endmill
Drilling holes using an endmill. Had to be very careful to not overheat. Ask me how I know – fires can spread very quickly on a vacuum table!!
Performing some steps, like rabbiting the edge of panels manually outside the CNC.
I would highly recommend an ATC to get the efficiency and help to use the right tool for the right cut in the job.
If you get a bigger machine than the plywood, there are decent ways to clamp down your sheet without a vacuum table. You may have to use tabs though depending on the parts. That requires more work to seperate the parts after cutting.
If you are only going to use one or two bits for most of your sheets, one thing to consider is getting an ATC spindle, and just swapping the tool manually. With the new EX controller, it will do the tool height measurement automatically, so the tool swap will take you about 30 seconds. However, you will need to stop whatever you’re doing in the shop to do the swap.
Not sure if anyone here has played with it on the new EX controller, but RapidChange do have a centroid version of their software so it should be do-able.
I do a fair amount of sheet work, and have used everything from clamps and dogs, to double-sided tape, to screws to composite nails. None are ideal.
Those wavy sheets tend to spring up a bit when cutting and bits of them are released from whatever clamping method you use - so you can lose accuracy (or the whole part in some cases). A vac table is gong to be best as with your cabinet parts, you’re usually going to have a decent vac surface area that will keep the panels flat, even when they’re separated from the main sheet.
I have some vacuum motors to build a vac table somewhere down the line, but as you say, it’s a bit involved. Or you buy a ready-made unit, which is slightly less involved, but still not plug & pray.
If you have a vac table, and want to do other things that use different clamping methods, you just have an additional spoilboard with dog holes/t-tracks/whatever that you place on top of the vac table. You lose a bit of Z that way, but that should only be a rare issue.
The advantage of the Avids is they are adaptable and configurable to whatever whim takes you this week. The disadvantage is you’ll need to do a bit of work to realise those whims. Lots of help here, but they all take time, so you’ll need to decide how much time you want to spend playing with the CNC vs how much time you want spitting out cabinet parts.
But once it’s up and running, the parts will fly out… provided you don’t come up with the next bit of tinkering…
