# I need some tips on making a clamping top to cover vacuum table



## Daner (Sep 17, 2017)

Hi all, 
I have a Industrial cnc table with a vacuum.
My isue is the motar is 3 phase and my shop is single phase, also my 100 amp panel is full.
Im basicly looking for a alternitive ways to clamp work pieces without useing the vacuum.
Thanks ahead!


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## difalkner (Jan 3, 2012)

Welcome to the forum, Danny! You can get a VFD for your motor and that will work just fine. I'm using a Hitachi VFD on my CNC to take single phase 240 and convert it to 3 phase 240 - works great.

David


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## Daner (Sep 17, 2017)

difalkner said:


> Welcome to the forum, Danny! You can get a VFD for your motor and that will work just fine. I'm using a Hitachi VFD on my CNC to take single phase 240 and convert it to 3 phase 240 - works great.
> 
> David


Thanks for the welcome David.
my 100 amp panel is fully filled up.

This is why in going with a different holding method instead of the vaccum.

Im new at this cnc, and I havent had the table running yet.

It came with a 1/4" mdf spoil board that they used with the vaccum, but how is the work piece held down to the spoil board?

Thanks

Danny


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## MEBCWD (Jan 14, 2012)

You might consider making a panel to mount on the bed that has t-nuts mounted from the back for use with clamps. 

Another possibility would be t-track, here is a link that 4D started on the subject: http://www.routerforums.com/cnc-routing/116298-easy-t-track-idea.html


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## difalkner (Jan 3, 2012)

Daner said:


> Thanks for the welcome David.
> my 100 amp panel is fully filled up.
> 
> This is why in going with a different holding method instead of the vacuum.
> ...


LOL! I read that and replied before it processed. Oh, well, it's still a reliable solution but you'd need a subpanel or more expensively, replace the 100 with a 150 or larger.

I use drywall screws and very simple shop-built clamps. You can see some here and on my YouTube channel.









David


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## UglySign (Nov 17, 2015)

Welcome Dan,

What's under the 1/4" spoil board? Phenolic/MDF top?

Possible to make a 2 layer MDF w/ tracks like 4D's?
Screw down w/ threaded inserts in between the vac channels.

Post a picture of your setup so we get a better idea. 

What about a low profile torsion box w/ tracks and bolt that down. MDF could get squirrelly and distort things.

Once the table is good to go, get a serious batch of jobs
and get a sub panel, phase converter/vfd. Then continue
getting serious batches of jobs. Seriously.


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## Daner (Sep 17, 2017)

*4x8 router cnc tabletop*

I now have the table wired up and can move the gantry back and forth up and down.:smile:
Thats where im at now.
Next is to load up the trial Mach 3 

Heres the table top

Thanks for your help guys

Danny


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## Daner (Sep 17, 2017)

The mdf spoil board in the photo is 1/4"
Showing the good side up. O the other side there are tooling marks.

I take it that the first owner used the vaccum, but Im wondering how he securred the work material to that spoil board?? any I deas?

Anyway I think Im going to pick up a sheet of 3/4 mdf tomorrow.

also look for some T-track


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## BalloonEngineer (Mar 27, 2009)

The MDF is porous enough that they laid the workpiece on top and the vacuum holds it. The MDF is to allow through cuts without damaging the vacuum table.


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## UglySign (Nov 17, 2015)

That appears to be a Phenolic top.

4D's method seems to fit best I'd say.
Maybe you can put threaded inserts into the top
and screw down the clamping bed. Set your tracks
accordingly. You can even setup threaded inserts
on that too.

Threaded Inserts


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## dovetail_65 (Jan 22, 2008)

A vacuum table top holds the 1/4" mdf sheet, you see tool marks becasue he laid the parts right on the 1/4" and the air pulls right through the 1/4" MDF AND holds the parts in place. The tool marks are his profile cut through to insure a good bottom edge(verse onion skin). This vacuum through the 1/4" MDF method holds the larger partsbeter than smaller parts. You would see marks for clamps and such, since you don't he was just laying parts right on the 1/4" MDF. This is actually the best way whenever you can get away with it.

Even if a regular old 1/4" MDF sheet works fine for vacuum through the spoil board there are few hints for sucking vacuum through the 1/4" MDF to make to even better for holding even smaller parts:

1) Paint or seal the edges of 1/4" MDF spoil board on all 4 sides. This blocks any air from being pulled through the edges giving a better pull to through top of the 1/4" MDF.

2) Skim cut(surface) the top and bottom of the 1/4" sheet about 1/32" before using it , especially if there is a shiny side to the 1/4" MDF . This allows more air to be pulled through the top of the 1/4" MDF.

3) Try to find whats called Light weight MDF for the 1/4" spoil boards and then do the above. 

4) Use a down cut bit for all the "profile through cuts", it tends to pack saw dust in the cut line that actually keeps the cut part from moving, gives the top edge a better cut and if you cut through a bit into the 1/4" MDF your bottom cut will be perfect as well. Plus, up-cut bits tend to grab and move the work pieces and give the top edge a furry feel.

I stopped using up cut bits on wood except for 3D bas-relief carvings years ago. I was taught to use an up-cut, but now I go against the the old timers and only use up-cut for metal and plastic now.

You may not have to do any of this, but doing so might enable you to secure parts even better, possibly giving you the ability to hold much smaller parts than you could if you used the 1/4" MDF right off the stack. 

I always like to the "pull the vacuum through the 1/4" spoil board" method best. Because through cuts can be made without touching your main table and you don't need pucks or any kind of clamps etc to hold the parts.

I would play with this set up. If your vac is powerful enough and you can get it to work, even just for larger parts, imagine rarely ever having to clamp or screw parts down, it opens up a different world. 

You may not be able to hold really small parts unless your pump is fairly large, so try my hints above. Ocne you do you will get a feel for what part sizes work with this method, if any. For small parts their are tons of other hints for clamping or using zone vacuum to make it work. Other than vacuum for the smaller parts I use a 3/4" spoil board to protect my table and use little screw's, other people use T tracks with clamps, etc. Some guys onion skin the parts that need be cut through so the parts don't move, I got away from that as it tends to leaves extra work. I want a clean cut on the bottom edge as well as the top.


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## Daner (Sep 17, 2017)

Hey guys, Thanks for spending the time to write your tips and sugestions.
Looks like im going to use a bit of all your Ideas.

Some day down the road I will get that Vac rigged up.

I have the sheet of 11/16 mdf now for a top, and I think im going to counter sink 6 screws through it to hold it down.

Danny


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## Dalton cnc (Sep 27, 2017)

I just wanted to add something really quick in the first couple of posts a guy had mentioned you need a VFD I believe what he meant to say was you need a rotary phase converter that will convert from single to 3-phase power 

I know you said your panel is full up but you could consider using 120vac vacuum motors instead of the big vacuum pump that you have now 

but for the spoilboard that you have now I would get rid of the 1/4" mdf I am not sure why that was ever on there its a little thin if you decide to look into using the vacuum at some point check out tupran ultralight mdf in 1/2" thickness for your spoilboard that will work great 

in the mean time get 2 sheets of 3/4" mdf and anchor the first sheet down to the the machine table in multiple places (as many places as you can) and then glue another sheet of 3/4" mdf on top of that using wood glue now you have a strong flat spoilboard that you can screw to surface the top of the new spoilboard and you are ready to go 

for workholding you can use 

screws
clamps 
double sided tape 
plastic composite nails (these are cool!!)

my opinion is that you have a vac table and you should use it I am not sure what kinda work you are using your machine for but I would love a vac table on my machine


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