Aluminum table inertia

[tlempicke]

I am in the process of replacing the table on my Buddy 48X48 with an aluminum table, similar to the one that Andrew Coholic shows on this site. By the time it is all done that table is going to weigh 140 Lbs. or a bit more.

Does this create any inertia problems with the X drive system? If it does can I get a larger more powerful motor to move the table.

[gerryv]

You might want to research foamed aluminum sheet/plate such as this example.
http://www.isotechinc.com/foamed-aluminum.html

[bleeth]

Tom:

My first thought is if it works for Andrew it should work for you! I would probably have a chat with the guys at SB though. It's less the weight of the table than the combined total with whatever you are cutting on it that is important.
I know a guy that cuts some pretty heavy aluminum on his without problems though. Not sure what his bed is though.

[Simops]

Does it make a difference whether you have a standard vs Alpha? Andrew has an Alpha.

Cheers

[tlempicke]

This past Christmas I got a Tabletop in addition to the Buddy. I immediately noticed that the machine was a good bit more accurate, particularly in the Z axis.
After reading Andrew's article I decided that he had a great idea and so I have bought all of the materials and am in the process of installing.
I will be using 80/20's 1030 material which actually has a smaller track than what Andrew used however it cost quite a bit less.

My table will be 60 x 60 and will wind up costing just under a thousand bucks.

I will be able to tell shortly if inertia is going to be a problem. I think I can also add a couple of ideas to Andrews already excellent thread.

[Brady Watson]

It should be fine if running an Alpha. A 4x8 Powerstick is no lightweight. If running a Standard, I'd adjust the VR settings to reduce abrupt moves & lost steps and keep the move & jog speeds reasonable.

-B

[Simops]

My table will be 60 x 60 and will wind up costing just under a thousand bucks.
.

Tom are you saying you are able to get a 60 x 60" table out of a 48" Buddy??!!

Cheers

[Ajcoholic]

Mike, the table is 5' wide - if you read my thread I started with a 60" wide piece of MDF, and my aluminum table is nearly that long but the linear rails took a few inches off the width. You can only cut of course 48" by 48" but often I have a larger sized piece I am working on, that can fit onto the machine.

Anyhow, After having my table and using it many times weekly since then (and some days almost all day, many days for a few hours) I would have to say the inertia of the top is not doing anything that my large, two layer MDF top was, ie, nothing.

I think my new aluminum deck is probably just slightly heavier than the old MDF deck.

But my machine works great - even large 3D carvings that are running for hours. No problem.

AJC

[tlempicke]

The length of the powerstick is the limit on the X axis but I think you could move the stops on the Y axis and get a good bit more space. If you use the keyboard function you can move the carriage almost all the way to the end of the gantry.

I am going to use a dial indicator to true the table top and plan to make use of this extra movement.

[Simops]

The length of the powerstick is the limit on the X axis but I think you could move the stops on the Y axis and get a good bit more space. If you use the keyboard function you can move the carriage almost all the way to the end of the gantry.

I am going to use a dial indicator to true the table top and plan to make use of this extra movement.

That's true to the left of the spindle but not so much to the right as the prox switch is on the left of the spindle......so you are limited to how far you can move the prox sw to the right....I got little more but not much really.

Cheers

[shilala]

An honest question...
Why not just go with 1/2 or 5/8" flat sheet stock? A 5'x5' slab would be about 500 bucks.
It'd take time to do all the layout and drilling to get it bolted up, but Dianne has a schematic with the dimensions that'd make it really easy.
I'm guessing the weight would be a lot less, too.
This is the way I've thought of going, I just haven't done it yet. It'll gain me about 1/2" of z, too.

I'm just wondering why you guys are going this way? I'm wondering if I need to do more thinking?

[Burkhardt]

A solid sheet of 1/2 or even 5/8 is actually not that rigid (relative to the mass). Stiffness goes with the 3rd power of thickness and an extruded t-slot profile spaces some of the load bearing surfaces further apart. A real sandwich would be even more rigid but not as practical as t-slot.

[Ajcoholic]

I could not work without the T slot table!

The Hubbard CNC stuff is great, I love mine as far. It's not crazy expensive and strong, flexible in terms of installation and only 1" high.

Solid top would still be in my case drilled and tapped full of holes. I clamp things far too often not to have that capability.

My top with the vac plenum and mdf spoil board and a half sheet of 3/4 material is well over 200 lbs and my machine works just fine. Probably close to 300.

[shilala]

Thank You, Gentlemen. That helps.