Cutting foam in 150mm lifts

LowRider CNC Advice
1

I have a project that I am looking at that is to make a plug for a fibreglass motorcycle body. The width is approx. 600mm wide by 2700mm long. I would machine it in 2 half’s so 300mm deep. The thought was to make it in 2 lifts of 150mm

I have read the documentation for the Lowrider and it talks about Z axis of 80mm. I am expecting this is because of tool pressure loading. Given I am going to use high density for the foam plug I don’t think there will be much load on it.

Do you think its possible for me to use a Lowrider over a MPCNC?
What do I need to think about?
Has anyone run a Z axis of 200mm before on a Lowrider?

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Have a look in this topic Taller LR3 build

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80mm Z-axis means ~40mm cutting depth.

So to get 150mm, you’d need a height of 300mm. That is basically impossible without the LR falling over. You’d need a drop table and a really long endmill. :slight_smile:

4

I also made a taal build: Growing pains

Works fine with styrofoam, wood i’m less enthousiastic. I think I leave this one for foam and build a LR4 for wood and other materials.

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I have picked up a cutter that’s 200mm long with a 150mm of cutting area. It’s bullnose designed for cutting foam. The diameter is 12mm. I know it won’t fit into a router so would need a spindle with an er collet.

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Could you point me to a picture of a drop table so I can better understand how it works

6

There are several ways to do it. Here is how mine used to be…

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Its 2 strips of 3/4" MDF stacked on top of each other to make it taller, you can go as high as you need. I still think you are going to run into troubles with not enough Z movement to cut as deep as you are wanting to. Is it possible for you to break your cuts up into shallower pieces of foam? If so you will be able to get a better cut and go much faster most likely.

That’s a big endmill for a LR. I think you will need at least a ER16 collet to get that size, but I’m not 100% sure on that. I run a 65mm air cooled spindle on my machines but it only has an ER11 collet so 7mm is as high as I can go (I think, 1/4" / 6.35mm is the largest I have used)

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Here, my best work: The gantry runs on those two boards left and right (like with Jonathan’s LR), but the spoilboard (which is not at the “normal” location) is a lot lower, like, a drop. That’s why that little guy is falling.

Drop Table

Or, to see it actually well made: Kelly’s got one that is like, 50mm deep, so he can cut ice. You’d need more. But the idea is clear, I guess:

1 Like
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I can split the model in to 75mm lifts. Just means I have to cut twice as many pieces. If it’s simplier to build and better accuracy then that’s probably the answer. I can get the foam in 75mm.

I like the lowrider as I could make it the full length I need to cut (would have to prejoin the foam to be the total lengh)

I could slice it the other way and make a much bigger stack. If I did this I would add some internal holes and use a dowel to locate them all

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Here is the body I am trying yo make

9

I really meant it with my drawing above. If that’s your one purpose for it it would not be too hard to make a table for it. You could just stack wooden strips for the height on the left and right.

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So I cut in 75mm, then lower the gantry and do another 75mm cut. I get it now.

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No, just do your 150 in one go. Your endmill is long enough, isn’t it?

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See those wooden slats on the left and right?

You can just stack like, 8 of those, that would be 144mm. Plus the “normal” travel, then you already have the depth you want. I don’t know how deep foam can be cut in one go though. :frowning: