Frage Aluminum T-slot table + vacuum table

Information about some accessories:

I replaced the original HPL plate with an aluminum T-slot plate (available as an optional accessory). This should be more rigid and it gives additional possibilities for clamping. The new machine table is 4mm thicker, so this leaves about 12mm space when using the original workpiece clamping system, enough for thin sheets and sacrificial layer. Replacing the table was very easy. First the X and Y axis end screws were loosened a little, then the table fixing was removed, the laminate table pulled out and the T-slot table slid in. Used the same procedure during tightening the screws as described in „First Steps” document available on Stepcraft homepage.

On the photo below a regular M6 nut and nuts for Isel T-slots (M5 and M6 threads, 25x10x3,5mm) are displayed. All these can be used for clamping.



Attaching a vacuum table:



The vacuum table itself has a work area of 400x200mm. It was the longest I could find that was narrow enough to fit onto the SC 600SF. Using it means that the Z axis travel is reduced (25mm + the rubber mat thickness). The connection adapter on this one is adjustable so an ordinary vacuum cleaner could be used.

The vacuum tables work really really well. They are excellent. Cannot say enough positive things about them - they transform the capacity of a machine for sheet material applications. However - while the tables are good value - the full vacuum solution is expensive.





few points

- MDF when machined on the top surface tends to bow and bend and often can pull the MDF contact point off the table causing the vacuum to loose grip


- MDF is porous so there is a certain amount of flow through the material which effects the clamping forces generated.

- the table you have purchased will work well with non-porous materials. But not as good with porous materials like MDF.


- if you use a vacuum cleaner / hoover to generate the vacuum you are essentially running with an active fire hazard. you are closing off the flow to a hoover and asking it to run hot with no air flow to cool the motor. be VERY careful. you need thermal overload and also under pressure release for proper safe vacuum operation.

- Proper pump system system for this sort of table is 500euro with all the safety fitting etc.

- a compromise can be to use a hoover and drill a hole to "port" the flow between the table and the hoover. For example drill a 20mm hole in a tube that connects the table to the hoover and then the hoover has some flow. Be VERY VERY careful here. you will kill hoovers and you'll have a fire hazard.


- the other option is to make an MDF vacuum table. MDF is porous and if designed well you can get good performance from a hoover while not over loading it with low flow . see here


Finally - spray adhesive is also your friend - whether on an ali vac bed or a MDF vac bed.


finally -DO NOT operate a vacuum table with hoover without supervision.

All,

The vacuum-table was my best investment as well.

I have this one and just use my vacuum cleaner for the dust, works completely fine.

I mounted the table on the original MDF and I have a t-slot as well which I exchange completely if I work with one (t-slot for metal or big parts) or the other (vakuum for the flat/slim parts).

Originally I mounted the vacuum also on t-slot but it was too complicated to unscrew my 60x40 table each time I wanted to use t-slot only.

it can also help to machine the top surface of the vacuum table to be super flat just a sliver of material.

Can you share the spec and model of your hoover that you use to maintain the vacuum?

My hoover is a super silent from Bosch.

Here is a picture when I flattened out my vacuum table with a 6mm tool:



Oh sorry, the cam inside:

Rory,
Aparently the MDF vacuum table on the picture is just a plate with a lot of holes just like the alu-table. I guess that you use the porous properties of the MDF to keep the vacuum even if the some gaps appear. Then the holes is just made half way through the plate or ?

Did an experiment with a vacuum gauge.

Left of the picture is what I had and right is what I needed to get for connecting the gauge to the existing plumbing system I use. Parts come from local household plumbing store, hardware store, pneumatics/hydraulics store and heating/pumping systems store.



Assembled unit. Used a piece of hose because the gauge has a G1/8 thread and I couldn`t find a suitable solid connector for that.



Connected to a vacuum table. The other end goes to similar plumbing connector that also connects my dust extraction to cyclone separator.



Tested the gauge with completely blocked vacuum cleaner (Kärcher MV3 P) and it indicated about -0,19 bar vacuum. Might not be completely airtight but that doesn`t matter because the vacuum cleaner needs cooling air anyway. Scale is from 0 to -1 bar so it is pretty useless for the use intended.

I am interested in the metal bed upgrade to remove bed-flex of the MDF in the 600 ; but what i really want is a WET cutting tray clamped to the metal bed - i wonder if there are some inverted "U" brackets to hold the sheets inside the wetbath? anybody else cutting FR4G10 fibreglass in water?

Hi Tikka. I was surprised by this statement of yours: "The connection adapter on this one is adjustable so an ordinary vacuum cleaner could be used."

Considering the repeated hazard warnings which I have no reason to disregard, this is revolutionary indeed. Especially when one looks at the price of "proper" vacuum pumps.

So, can a common vac cleaner generate and maintain adequate pressure for these tables, and what happened to the overheat risk? After all CNC-Plus do sell their own range of vac pumps.

Cheers!
Miguel

Hi SpydaTuSefen,

Surprised you want to cut FR4 underwater. I've milled quite a few circuit boards and find that the standard HF dust extractor system is quite adequate - in fact sometimes I haven't even bothered with that for a small job.

I use a 3mm 30degree carbide engraving cutter set to a cut depth of 0.1mm (.004") and can reliably cut tracks 0.25mm wide.

FR4 will absorb water, so you would be wise to minimise exposure and dry it out after milling

Peter

Hi guys,, i'm trying to figure out if buyig a stepcraft could be a good shot for my need. One of the things i'd like to do is cuttin dry glass fibre with a drag knife, if i use a vacuum table could the hoover give enoght clamping force (at least for a while) or do i need to buy one of those pumps?
thanks