Hold-down tapr for Rowmark Flexicolour?

[Michael Hunter]

I have just done a big job (20"x32") on Flexicolour black/white and since the engraving was heavy, was paranoid about the sheet warping and going out of focus.

I knew that the 3M double-sided tape I had was nearly permanent, so I bought some carpet tape from the local hardware store and stuck the sheet down with that.
The carpet tape LOVED the back of the Flexicolour and I had a real struggle to get it off, followed by a considerable time getting the last of the glue off with white spirit (turpentine substitute).

Anyone got any ideas about a better way to stick things down?

Thanks

[John Noell]

They do make sticky mats for lasers. The matas are expensive - and sometimes too sticky I hear. You can also use magnets. The rare-earth ones out of old hard drives are quite slim and EXTREMELY strong. (Be careful.)

[Ross Moshinsky]

We use engravers table tape from JDS. It's just the right tacky. Just don't use a ton of it. Space out the strips 6" and you should be fine. Another trick is to wet your finger and run it along the tape. I'm sure you can find something similar from a local distributor.

[Michael Hunter]

Ross - In my ignorance, I thought that table tape and carpet tape were the same thing. Live and learn!
I think your No. 2 idea is good if I have to do another one quickly - I will spray the tape with water first before placing the sheet.

John - The magnet idea is good too, except that the whole of the laser bed is covered and engraved on (just 1mm round the edge gets cut off) - no room for magnets on this job.
The sticky mat stuff is VERY expensive in the UK, but worth a thought if the job expands (as I hope it will!)

Thanks for your ideas

Viktor separately emailed suggesting a vacuum table. More hi-tech than I was thinking of, but again worth considering if the job takes off.

[Joe Pelonio]

There is a very cheap and weak double sided tape sold at the office supply stores, looks like masking tape but sticky on both sides that works, but you still really only need about 4-6 pieces 1" long strategically placed.

[Michael Hunter]

Here's the hold-down solution that I have been working on (very part-time) for the last few weeks.

The vacuum table is now completely finished and tested, but I still have to make a hole in the front of my Epilog for the suction pipe.

Made from 6mm baltic birch ply with a 1.2mm aluminium plate protecting the top. Total cost of materials is about £25.
There are a mere 1,782 3.5mm holes in the top - drilled with a hand-held Makita (just too mean to have the plate CNCed).
The internal supporting honeycomb is overkill : the spacing could easily be increased by 50%.

[Robert Walters]

drilled with a hand-held Makita (just too mean to have the plate CNCed).

Um, don't you mean sadistic???

How is the vacuum in the diagonally opposite corner from the vacuum hose?
It seems with the supports it would be less in that area, but I know vacuum has different attributes compared to being pressurized.

[Michael Hunter]

Robert

As far as I can tell, the vacuum is even across the whole top.
In use, the "spare" holes not covered by the workpiece are covered up with strips of paper. This means that once the (partial) vacuum has been established there is very little airflow through the honeycomb.

And yes : drilling the holes took ****** ages and my arm still aches.

[Mike Null]

Michael

Nice work. How did you run the vac hose into the cabinet so as not to lose the exhaust of the laser?

[Michael Hunter]

Mike

The Epilog has a removable sheet steel front panel below the main air inlets.
I'm going to cut a hole in it only just larger than the suction hose, so when the hose is in use it should not make much difference to the airflow for the exhaust.
For normal use (without the vacuum table), there will be a flap which swings down and covers up the hole.

To protect the suction hose from rubbing on the edge of the hole in the panel, I have made ply surrounds with radiused inside corners.

(The exhaust airflow over the work is rather poor when the front panel is off, otherwise I would just run it open).

[Mike Null]

I wonder if you might not get smoke and odor through the vacuum. It would be great to exhaust the vac with the laser exhaust.

Or hook the vac to an air filter.

[Michael Hunter]

I don't think that it will be a problem, but I will find out next week!

Because there is very little airflow through the vacuum system, I should only see any problems if I manage to cut across a lot of the holes in the top-plate.

If the worst comes to the worst, I can always make another hole in the front panel and vent the vac back into the laser cabinet.

[Mark Sipes]

I have covered my aluminum table with steel sheet stock and use plastic covered name tag magnets to hold down the job. On the large jobs the magnets can fit inside the cut line. Trotec 25 software allows for previewing job placement on the table.

This also allows placing a sheet of paper under a job that gets cut through thus preventing the sticky residue from forming on back of the LM (romark) material. I can also pre-tape a job and cut through the tape and backer reducing individual taping after running the job.

Mark

[Michael Hunter]

Thanks Mark

Magnets would have been a saner solution but ...

The customer wanted the piece to be as big as possible, so the cut lines were 1mm inside the edges of the bed.
Apart from a small amount of space around the edge, the whole of the piece was engraved with 10mm diameter circles spaced 5mm apart in both directions (think polka-dots).

... no space for the magnets!

[Carrol Fleming]

I have just done a search on ebay for low tack double sided tape and found quite a few options for removable stencil tape and mats - never tried any but probably would in the future.

Carrol

[Michael Hunter]

All tidied up now.
No problem with smells coming out of the vac - nothing comes out of the vac!
(And I was cutting awful smelly stuff : rubber/cork gasket material - which was held really flat)

[Richard Rumancik]

Michael - what are you using to generate the vacuum? (And please don't say shop vac . . . or you might be seeing smoke coming out of the vacuum.)

[Michael Hunter]

Unfortunately it is a light industrial vacuum cleaner : it's life might not be long.
The motor does seem to have adequate cooling of its own though (it doesn't depend on the airflow through the dust catcher).

[Richard Rumancik]

If it has it's own cooling path then you might be okay. Many shop vacs are cooled by the exhaust air so can't tolerate being stalled (zero air flow). For those, the only solution is to allow at least some air to bleed through, but of course this results in loss of some vacuum. Vac motors tend to run at high speed, usually overdriven, so it doesn't take much to overheat them.

[rich santana]

back to the thread question, i use standard spray adhesive on pattern cardboard, let it get past tacky and stick your material. it releases pretty easy. i use this for paper and it works well without getting blown off by the air assist.