After almost a year of planning I removed my table & LR2, so I can upgrade to LR3.
I decide to build a solid table with cabinets and a hotbox for epoxy curing below the workspace.
It has a dimension of 100x244x95 cm and is pretty solid. Now that I am nearing completion I start to doubt on the spoilboard. In the past I just taped/screwed the pieces down to the board. Ultimately I will be using vacuum to hold my pieces, but for now I am looking for a simpler solution.
I am doubting between T nuts and T tracks.
The first is some effort to add, the second a bit expensive.
If I would go with t nuts, I will drill the holes with the LR3, on a 10x10cm pattern, and make sure there is some room to cut into the spoilboard.
With t tracks I would add them a bit wider due to the costs.
You can achieve most of the benefit of T-track without the cost of the aluminum by putting a rabbet along the edge of strips of spoil board material and mounting them (with the rabbet down) far enough apart to let a (square) nut or a bolt (I like brass toilet flange bolts) slide between the strips. The rabbet holds the edges of the bolt or flange of the nut and the shaft passes through the slots between the strips. If you’d prefer a grid pattern to clamp to, just cut MDF squares instead of strips and rabbet all four bottom edges before mounting them.
I’d screw the strips or blocks in place with counter-sunk (or counter-bored) fasters sunk below the depth of the thickness of the top “lip” of the track. You’ll then be able to resurface the spoil board a couple of times without being at risk of hitting the hold-down hardware, as you’ll have shaved away the “track” before getting to the hardware depth.
I don’t think there is a winner here between t-nuts and tracks. The “best” partly depends on the kind of projects that are your focus. A few random observations from a Primo owner (I understand that the Lowrider experience is different):
In addition to Tom’s suggestion of a rabbet (which sounds like a great solution), there are specialty bits for cutting t-track slots, and an endmill plus a slot cutter can also cut t-track slots.
I’m not sure if you are referring specifically to t-nuts, or are using the term more generally. Most of the builds I see use threaded inserts. You want inserts that have a flange and therefore will have to be installed from the bottom side of the spoil board. Threaded inserts installed from the top tend to pull out. Personally, I used these inserts. They are short enough to allow me to surface my spoil board multiple times, and I’ve never had one pull out.
I made the mistake of placing my inserts on a rectangular grid at a 65mm spacing. For some types of hold down solutions I like to use, this spacing is too large. Plus, there are many inserts that either have never been used, or only used a couple of times. When I redo my spoil board, I plan to concentrate inserts in the areas that I commonly use, and have only sparse inserts in other areas.
Nothing prevents you from having both. Maybe you want an area of reasonably tight threaded inserts for smaller jobs, and some sort of a t-track solution at a large spacing for working with larger, sheet projects.
There are other solutions beyond t-nuts and t-tracks including solutions that use evenly spaced holes for dowels or pipe or similar, and some sort of compression clamp like cam clamps. If you are primarily doing sheet goods, this seems worth considering.
As someone who has a suction table: as soon as the wood is warped a little, it might not hold. Smaller workpieces do not hold. As soon as you have cut out a lot of shapes it does not hold any more etc. I am going to buy T-tracks that fit M8 screws, spaced around my cutting area, to hold it down at the edges of need arises. For me that is the cheapest solution. I don’t want to have additional holes in my “suction MDF” (for the lack of a better term).
That´s actually a good idea!
I am affraid that the toilet flange bolts are not available in my region, but this actually an idea I will consider. Do you have issue´s where the edge is overhanging (in terms of strength)?
This looks like a bonus to Tom´s idea. That way I can use just 1 spoilboard, instead of mounting multiple ones perfectly alligned to eachother.
I was talking about the general ones. With a flange. I would cut a part for the flange, and the nut itself. Flip the board and drill the last part by hand for a clean board (and not cutting in the below table top).
The investment for like 300 tnuts would be 30 euro, but costs a lot of time to add all the nuts as I would make the grid 10cm apart.
The suction table is a long term solution for me. As I am doubting on using my compressor or vacuum pupmp, or regular vacuum cleaner.
I would be cutting plexiglass and thin sheets of plastic (roughly 2mm thick, that comes from a roll so I would curl without suction table).
I appreciate your insights though, as I believe there isn´t much insights on this matter.
I was talking about the general ones. With a flange. I would cut a part for the flange, and the nut itself. Flip the board and drill the last part by hand for a clean board (and not cutting in the below table top).
I put a piece of scrap wood between my spoilboard and my base board, then used my CNC to cut the pocket for the flange and bore the hole for the insert in one job. The scrap protected my base. I did some test bores on scrap, and found the best fit for the insert was a hole a bit smaller than the specification.
I have only been using LR3 for a couple of months. Installed tracks, have yet to use or need them. I use the painters tape and super glue thing. Course everything so far is 3/4 box store stuff. Thicker material I think would need better clamping.
Thanks for the advice on putting a scrap below the board. It would save me a lot of time doing so.
I only have used tape on acrylics, might want to try it on wood too. Great suggestion.
The only downside I can see is that my doublesided tape is very sticky and hard to remove (on acrylic there is a protection film, so that is not an issue).
I believe I will try the T track bit and cut slots into the MDF ( the bit is as expensive as the amount of t-nuts I would use, but the bit could be used for other purpose too).
Already found it is best to cut a straight slot first before using the t track bit so I wouldn’t burn the mdf.
Now my question is whether I use m6 or m8 bolts for the track. Any feedback on that, would be welcome
I only have used tape on acrylics, might want to try it on wood too. Great suggestion.
The only downside I can see is that my doublesided tape is very sticky and hard to remove (on acrylic there is a protection film, so that is not an issue).
The tape method Carl was referencing is using painter’s tape and superglue. There are lots of videos on this method. Here is one.
Also, here is a double-sided tape that has worked for me with my CNC. Likely it would be too expensive for large sheet jobs, but it has worked well for my smaller jobs.
I was headed in the vacuum direction until I saw a youTube video that pointed out that it wasn’t great for small pieces because there is so much open area on the table that vacuum didn’t work as it should. He also pointed out it creates a lot of extra noise and that some of the vacuum pumps use 10+ amps each, so more electricity.
I think I am heading towards a table with alternating t-tracks and spoil board strips so the spoil board can be replaced as needed.
That seems like some solid feedback.
I’ve decided to cut the t track into the wood with a special bit. Next I’ll be installing a removable vacuum system for this jobs when I need it.
FWIW, I set my t-tracks up with 4" strips of mdf between, using deeply countersunk screws to hold the strips in so they don’t get hit by facing operations. It has worked out awesome so far. I always have smaller strips of mdf around… so only requiring 4" strips means I can use a lot of otherwise scrap wood to replace spoilboard strips as needed. Prepping new strips for install is easy… just run them through my table saw, drill counterbores, and screw on. This is much easier long term vs remilling slots for the t-tracks every time. It also allows you to only replace what’s needed, vs the whole thing when only a small part is buggered up.
My side channel blower is much quieter than the shop vac, you can’t really hear it. What you are right about is that small parts do not hold, but bigger sheets do easily, except they are really crooked.
For that I also installed some T-tracks on the sides.
That makes sense!
In my case that wont work as I used one giant MDF plate (on top of the table) for the LR3 to run on, and to use as a spoilboard too. So cutting tracks makes sense this way.
Yep that’s how vac holds like to work… more area lets the pressure apply more force. I’m not sure how well this works, but I was told by a talented guitar maker that using just milled MDF and tape is enough to hold down things like pearl inlays etc. Like the MDF is porous enough or something IDK… he swore by it, but I can’t quite wrap my head around how it works so well I guess (maybe with no through cuts?). So I haven’t tried it myself. Also, this was with a full on vac pump, which I don’t have.
The theory behind it is indeed that MDF is porous enough to suck air through, although it depends on the MDF quality on how well this works (the used glue is the key factor).
Some users make a plenum board to hold the pieces and loose power that way. It is best to add the bleeder board on top, so you do not have to tape the area´s that are unused. The MDF in the bleeder board should be enought to keep things down (obvuiously your pump is also key in this story).
you can read some more here or look ar Philipp´s build.
ohh, these seem to be fun too
The first link is what gave me a lot of orientation. For the first build I did use MDF and tried to seal it, for the second one I cut the grid in plywood and glued 8mm plywood around the edges to stop the air from escaping there. Works well.
