securing a spoilboard

[podzilla]

I apologize if this has been covered on here before or if it seems like a stupid question but: We have a Precix 9100 router with a t-slot table that has a hard black plastic top on it, with holes that allow the vacuum to draw thru a spoilboard. There is no grid to distribute the vacuum, precix instead relies on using many small holes to do the job. I've been using this router for over two years now and consider myself pretty well versed, however there's on thing we've never really gotten to work properly: the vacuum table. I understand the concept of skinning a piece of MDF or LDF to allow a vacuum to be drawn to hold parts down. We have tried doing this but met with an issue; how to properly secure the spoilboard to the table. On a shopbot, you can simply glue or screw it to the plenum piece, but with the t-slot table, we don't have that option. My question is simple: how does one properly secure the spoilboard to a table with a permanent plenum surface? Any helpful ideas would be HUGELY appreciated, since we are starting a giant job cutting some furniture grade mahogany plywood this weekend. Thanks in advance.

[lgalla]

My friends Thermwood router has nothing holding the spoil board down outher than the vacuum.Skinning the MDF is to make the surface parallel to the gantry.One trick is to use a 1/8" spoil board on top of the 3/4" MDF.Again the vacuum holds it down.Sorry I do not understand why the spoil board has to be fastened?

[lgalla]

Podzilla I re read your thread.Are you saying the vacuum will not pull the spoil board down?If so even if fastened down it will surley not hold down parts.With small holes your hold down pressure will be minimal.To hold down a 4X8 through an MDF spoil board you need a 20HP vacuum pump.Larry

[podzilla]

thanks for the quick response. We have a 3phase FPZ regenerative vacuum blower that came with the table. I don't know the specific model number but it looks similar to this one. http://www.fpz.com/modules_cms/prcat...hp?cc=11&pc=18 It makes one hell of a noise when turned on and does have enough power to hold a single 4x8 sheet to the table well enough that I have no chance of moving it while the vacuum is on. The problem comes when we try to use it with a surfaced spoil board and piece of stock on top- it does not seem like there is enough pressure to hold both the spoilboard to the table as well as the stock piece on top, and as soon as the machine starts profile cutting, stuff starts moving around. I made a quick diagram to explain what i mean:




I'm saying that there has to be something between the spoilboard and the table to keep the spoilboard from sliding around during cutting. I've searched high and low for this information and can't seem to find it anywhere. I figured it was typical to use double stick tape or glue of some sort but before i go marking up my table I just wanted some feedback from other people.

[lgalla]

We had the same problem,but the the outher way around.Our vacuum would not hold when cutting plastic.Sorry got to run.I will have a look at our set-up and post this evening.
Try http://www.allstaradhesives.com/
Larry

[ger21]

All Star makes some double faced tape for this application. What you might want to do is get some low density or lightweight MDF, which will allow much more air to pass through it.

[podzilla]

THANK YOU! Exactly what I was looking for. I just ordered a roll of their tape. In the meantime while I wait for it to be delivered, do you think that 3M mounting tape would also do the job?

[lgalla]

Hope your problem is solved.Just currious.The vacuum table never worked for 2 years?
Did Precix not help you with the problem?
larry

[podzilla]

Its not that the table didn't work, its just that we never set it up properly. Precix was little help, it seemed like even they didn't know how to use their own system. They (or at least our tech support guy) had never heard of the idea of pulling a vacuum thru MDF. It just felt like they included the vacuum table because everyone else was doing it. I've been cutting with the vac table all weekend and all I have to say is "where have you been all my life?"

[lgalla]

Hay Pod,
Thank you for the up date.Some times you try to help out and never hear from the guy again.We like to see that our help was use full.Really appreciate your responce.
Many CNC buyers get zero support after signing the check and the customer thinks they are the blame.A favorite after sale responce is"you did not purchase our software so we can not help you"
Keep us posted on your success.
Try the 1/8"spoil board on top.I don't know why it works so well.
MDF manfacturing is a thick paste put in a press and squeezed down.This results in two dense skins and a low density core.It helps if you seal the edges with tape.Give it a try.
Let me know if it makes a difference.
Larry