LR2 Plate Thickness

LowRider CNC Advice
#1

I’m looking at tearing down my Lowrider to build the LR2, couple of questions;

Can I cut all the plates in 18mm Ply? My current 611 plate feels a little flimsy at 12mm and I’m wondering if 18mm is going to cause me any issues.

I’m considering building a table like this from aluminium square section, I figure it’d be straight and reasonably rigid, perhaps lift into the ceiling when not in use. Is there any reason I shouldn’t? Except the fact that it’s going to cost me money.

The big issue with my last build was the flatness of the table, the Z bars rubbing on the side of the table and I think I can see a twist in the X-rails with cuts that are too fast (that probably is the problem right there)

 

 

 

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#2

That’s pretty thick. I think half inch(12.5mm) is about as thick as you want to go. You start losing end mill length if the plate is too thick. Depending on how you attach the aluminum square tube, it should be alright. Welded would be kind of hard, the heat will warp them.

#3

The aluminum seems like it would have to be huge to be rigid. And have you actually figure out the price? I think it will be pretty shocking.

Was your first build just dimensional lumber? 3/4" Plywood, ripped into 3" strips, is pretty rigid, and flat. My low rider is only 4’x5’ (total size, so about 3’x4’ cutting area) and it’s pretty flat. It’s technically a torsion box, but it’s only got 7 pieces.

#4

Welding aluminum is a terrible idea. Welds are weaker on aluminum. They don’t have the same strength as solid aluminum. The welding process make the material brittle. Aluminum is soft too and can distort. Stainless steel is suggested and I, a real cheapskate, have decided to go that route. Were it me, I would create 3D plastic connectors and use structural alum thick wall tubing. I like the idea of flying it up to the ceiling.

#5

My current table is 2 mdf sheets with 100mm ripped mdf sheets acting as ribs, the garage kind of fluctuates in temperature and humidity which doesnt help things.

In terms of price the aluminium isn’t that horrific, around $60-80nzd for a 2.5m length (80*40?), I’ve got a friend I can go through who can get a discount rate on that too.

 

I was thinking I could weld or tekscrew the joins. The other option could be steel frame, but I hear a lot about that warping and twisting.

 

I’ll stick to 12.5mm with the 611 plate though. Maybe look at using a different material.

#6

Really? Have you bolted everything on. If you have a closer look, once everything is bolted on there is very little material that can actually move. You can not just look at one part, as with all my machines it is a complete system. The router base is actually doing most of the work.

I am easily running 1/4" ply, 1/4"MDF is even more rigid. Anything past that is just a waste of Z axis rigidity/height.

#7

If you use steel and are careful with your welding it shouldn’t warp/twist. You want to make sure to spread the heat around and take it slow. Tack each side/face of the steel square stock and the. Go back and finish welding each section, skipping around a lot to distribute the heat. The buildup of heat during welding is your main source of warping. Also, before you tack weld, make sure everything is square and level and clamped down in all directions. This will greatly reduce your risk of warping. A lot of times, warping comes from the first tack welds which cause the steel (or any metal) to move in the direction of the weld - this happens as the steel at the weld point cools and contracts.

#8

I’ve begun making a LowRider v2. Quick Q about Y plate thickness.

My understanding is the Y plates are supposed to be cut from 1/2" plywood. I have a sheet of 3/4" plywood. Is there a problem with using 3/4"? Or is use of 1/2" only for cost savings? I also have some aluminum. Is it overkill (needless over engineering) to make the Y plate out of aluminum?

I gather the 611 plate that holds the router is 1/4" out of a desire to keep the weight down.