Does someone have recommendation for screws that will hold top MDF spoil board to the bottom layer MDF? I have some âcabinetâ screws that have the nice flat washer head on top but the threads are not very coarse so worry that they will not work well.
Itâs a bit of an odd question IMHO. First, any decent bolt supply house will have the right screws. Second, Amazon has âparticle board screwsâ which may or may not be similar to MDF screws. You might check AliExpress if you are not in a hurry. You didnât ask but I would suggest flat head screws - they will give you more room for surfacing the spoilboard.
Having gotten that off my chest, I would bet that the vast majority of people just use common wood screws. You will likely have a whole bunch of screws and the load per screw is absolutely minimal.
You seem to be concerned with following optimal procedures ⊠did you know that pre-drilling is highly recommended in MDF? I suppose since you are not going into the edge it wonât make much of a difference but that would be the proper way. Some of the âcabinetâ screws I have seen do not have a sharp point and they definitely require pre-drilling with the exact size drill that is specified.
Since you need to recess the screws, it makes sense to do the holes directly on your mill. You can drill the right size hole in the baseboard, do a hole a tad bigger through the spoilboard and then do the recesses for all the holes. I would drill/bore these with a flat bottom as the MDF will deform for the screw head.
I would never attempt to drill the recess by hand as (IMHO) the depth is quite critical (I suppose if you have a depth stop you are golden but I wouldnât do it by hand since you have a perfect machine right in front of you.
I think I recess by half the thickness of the spoil board. If you are using 3/4 MDF I would consider recessing 3/8 or even 1/2". Do not overtighten the screws as they could easily break out the bottom of the recess (and it isnât required either)
Some people use inserts in the baseboard and use machine screws to attach the spoilboard. This pretty much requires doing the job with the mill to match the hole locations of the insert with the bolt holes through the spoilboard.
Sorry for taking a simple question and replying with way more info than you probably wanted.
Bit of an afterthought: Drywall screws âŠ
I had some 1" âwasher headâ/cabinet style screws that had very course threads on them which I thought would be perfect but could never find them anymore. I was also asking since I was getting paranoid after just using the cabinet screw I was going to use for the spoil board in a softwood and it did not hold at all. Would the MDF hold the cabinet screw better than a softwood? (was white spruce)
Sheetrock screws. Very coarse
Thatâs what I did but I have a Baltic Birch base, not MDF. Inserts will allow you to replace the MDF spoilboard with screws at the same location.
FWIW, you want to avoid bridging when screwing two pieces together. You can do that by drilling a clearance hole in the spoilboard. Or making sure your screws are not threaded all the way to the head.
GRK screws could work and are easy to find.
Be careful not to screw into your aluminum cross bars.
Another option is to bolt it down by putting threaded inserts into your sub-spoilboard plate, then use countersunk nylon screws in the actual spoilboard. Keeps from accidently damaging a tool by clipping a screwhead if your cut depth is off.
3 Likes
Looks like a Truss Head screw to me. Pocket Hole screw would work as well (same/similar head). Either would be a good idea.
I used regular counter-sink wood screws on mine which I counter-bored about 1/4" as well and these have held up well.
DavidB
I have build a lot of cabinets over the past 45 years of woodworking. I could go down the rabbit hole about screws and the correct screw for the application. But, to answer your question, you are on the correct path. However, you need to purchase the course ones. Some manufactures call them Particle Board Screws. Think of Pocket Hole Screws. Fine ones are for hardwood and course are for softwood or plywood. To mount my CNC machine on I first made a Torsion Box. I used 3/4" plywood to make the torsion box which was glued and screwed together. I then checked for flatness and sanded where needed. I have a master straight edge to set up my equipment so why not use it. I then mounted 3/4" plywood to the top of the torsion box. I mounted my 3/4" MDF spoilboard to the plywood using Particle Board Screws. Only predrill the holes in the MDF and not the plywood. Screwing the MDF to the plywood is like using Pocket Hole screws. You only predrill the first piece (drawer front) and not the second piece (drawer sides). Now your second question, yes the Pocket Hole Screws (the course ones) will be OK. Hope this help.
1 Like
I would like to clarify this if I may ⊠the pre-drill in MDF is a âclearance holeâ and not a âpilot holeâ ⊠(just in case there is any confusion).
1 Like
If Iâm using 3/4-in waste board, I will counter bore 1/2". Leaving a quarter inch at the bottom provides plenty of strength and gives me lots of room to resurface the top. I lay out a grid and put a screw every 12 in or so
1 Like