Frage Workholding during machining

Its very important to make sure the part is held well during machining. Especially during sheet machining. When you clamp at the corners / either end of a big part the part can move and rise in places. This causes vibrations and poor finish. It can also create irregularities when engraving as the parts movement in Z causes different depths to be machined.

You need the part to be fixed and flat for good results.

3M contact adhesive does a great job.

Make a sacrificial layer for your SC tabel. 5-6mm ply/MDF. Stick this to the SC bed with spray adhesive. Then use a combination of clamps and adhesive to tick your parts to the table.

A gentle sanding after the machining usually removes the adhesive well. A lot of the engraving plastics, perspex, polycarbonate and acrylics have sticky back plastic on the finished surface. The sticky back plastic can simply be removed along with the remaining adhesive to leave a perfectly machines material finish.

Any of the sheet work we show will be done with spray adhesive. It also prevents finsihed parts from moving when the outline is completed. Free parts internally can hop and move and get damaged by the cutter as they are typically not help. The spray adhesive really helps here.

A good strong degreaser will remove and adhesive from the SC table if you ever want to replace your sacrificial layer or go back to the bare SC table.

Great points Rory.

I have glued my sacrificial layer to the hardboard and then I screw into the sacrificial layer in different locations, this seems to work also. I tend not to use the clamps at all anymore. If you identify gaps with in the design and make the router bit go to them using the "goto" tool mark the point and screw in there, just make sure you have referenced first!

How does the metal bed help in this scenario Rory?

Alex

Yes - but be careful as you cannot mill as hard when you use just the glue - there is still a risk it will shear on the glue line and move. You are relying on your preparation for the adhesive 100%. any organic residue from finger prints or contamination (chips / debris) can all compromise the glue line.

Good idea to screw the sacrificial layer down - make sure to counter sink - as its always a good idea to keep bolts and screws away from the cutting plane.

On the S600 especially - if you over tighten the clamps you can bend the bed a little. This is a big factor for engraving - not so much for milling when you are milling through a little over the thickness.

The Tslot bed adds a lot more rigidity to the machine - it keeps the X,Y plane exceptionally flat even when clamped. This could also be realised by a stiff piece of 18mm ply as your sacrificial layer. The Tslot with Tnuts can be helpful for clamping smaller parts locally.

We will have a vacuum table and pump (relatively low cost) tested very soon. These work exceptionally well for non-porous sheet work. We will post the results.

We will also soon have a "Make your own vcauum table for your STEPCRAFT" out of MDF. when clamping porous materials for machining the vacuum table requirement is a little different. More information coming soon.

By the way - what we say is not the only way - very open to others suggestions?

Rory schrieb: We will also soon have a "Make your own vcauum table for your STEPCRAFT" out of MDF. when clamping porous materials for machining the vacuum table requirement is a little different. More information coming soon.

I'm curious about it!

Currently making on for machine with 1300 x 900mm travel out of 38mm MDF.

When its finished will use the vacuum table to make tables for STEPCRAFT machines too.

Needs to be tested first. Should be ready in next weeks.