What do you use to hold things down?

[Greg W Watson]

For instance I need to vector cut something out 3mm birch or similar, but the wood even though stored flat has a bow to it. What do you use to weigh things down on your table to make sure they stay put?

I use magnets when I am etching but they don't work on the cutting bed.

Greg

[Keith Upton]

I'm interested to hear what others have to say as well. I've got quite a few products that I'll be cutting out of 3mm Baltic birch and it is always a little warped no matter how I store it.

[Jason Hilton]

Depending on the thing I'm making, I use a couple different techniques. Most often, especially when doing two sided or precision placement engraving and cutting, I make an index table that a workpiece can be secured to with nylon screws. This way I can lock the index plate to the bed and lock down my work piece to the index plate. It's great for repeatability as well, since I work on a maker-shop machine with limited available time. I imagine when I get my own machine I'll do things the same way.

[Tim Bateson]

Sticky matte for RowMark. Nothing for birch. If it's badly warped, I don't use it. Just a little warped - very little, I use pieces of scrap marble.

[David Somers]

In asking this, please keep in mind I don't have a laser yet. The only honeycomb I have has honey in it.

I was curious though. Has anyone tried making something similar to a wood workers Bench Dog for use on your honeycombs? A bench dog is typically a cylinder, sometimes with a lip on the top that gets inserted into holes in your work table and used either as a point to push against with a vise, or to hold things by themselves. Friction and the slight cant that is caused by pressure being applied to it are what keeps it down.

In the case of a honeycomb your dog would need to be a hex shape to match your table rather than a cylinder. But that would be fairly easy to form. They are simple, easy to put in place and easy to remove, and low profile which would be important on a laser bed. If they would work they would be useable on both steel and aluminum tables. You wouldn't need much holding force to keep a slightly bowed 1/8in ply flat so any stress placed on the honey comb should be pretty light.

Any wood workers out there with lasers who have dinked with this idea? Any merit to it?

Another thought might be a cloth divers weight. You can get them in various sizes/weights. They are filled with lead shot and usually made of neoprene or nylon. If you have access to some lead shot you could make some easily in whatever size and weight you wanted?

Dave

[Keith Upton]

Sticky matte for RowMark. Nothing for birch. If it's badly warped, I don't use it. Just a little warped - very little, I use pieces of scrap marble.

Not using warped sheets would be ideal, but not sure that's practical in my case. I have to do production runs (my first run will be for 2000 pieces) of these game rulers:

http://sailsofglory.org/attachment.php?attachmentid=8465&d=1390325888

I would end up with a lot of unused sheets if I could only cut the nearly flat ones. And being that I'm cutting a full sheet with almost no dead space, laying a largish object on the sheet while cutting to hold it down would not work very well either. I guess I could run it as two separate files, doing one half of the sheet and then the other.

Once these are cut out, any that are warped badly can be wet and flattened out under a milk jug full of water in a couple of hours. Unfortunately, I've not been able to that with a full sheet.

[Mike Null]

I pretty much gave up on thin baltic birch and switched to using acrylic. Less waste and a very good look. I realize you may not have that option.

Dave
the honeycomb is very thin (possibly .010") and somewhat fragile for the application you suggest.

[Dave Sheldrake]

Dave,

I have a NdFeB magnet trick that works on the Rabbit aluminium cutting beds, holds just about anything flat including 1/4 warped ply :) I'll ping you an email with the pictures.

cheers

Dave

[Tim Bateson]

Not using warped sheets would be ideal, but not sure that's practical in my case. I have to do production runs (my first run will be for 2000 pieces) of these game rulers:
I would end up with a lot of unused sheets if I could only cut the nearly flat ones...

I buy my Baltic Birch from a fellow Creeker & seldom have an issue with warpage.. unless I lay a sheet in the wrong position for awhile.

[David Somers]

Dave! An aluminum magnet? I am anxious to see this!! <grin>

Mike Null! Thanks!! I was wondering how thin and fragile that aluminum honeycomb was. The few steel ones I have seen seemed like they would be OK. Bu am just guessing of course.

Dave

[Greg W Watson]

Dave,

I have a NdFeB magnet trick that works on the Rabbit aluminium cutting beds, holds just about anything flat including 1/4 warped ply :) I'll ping you an email with the pictures.

cheers

Dave


Please do greg @ cutoutlaser . com

[Mike Null]

I have used the BB that Mike Kowalczyk sells and had good success with it but still had an issue from time to time. If I need 3mm BB he is my go to guy.

It's sometimes possible to use a concept like fender washers and wing nuts.

[Ross Moshinsky]

Make a slide in fixture that will hold the material flat. Doesn't control what will happen after it is cut but it certainly will keep things flat while cutting

[Greg W Watson]

Make a slide in fixture that will hold the material flat. Doesn't control what will happen after it is cut but it certainly will keep things flat while cutting

would you happen to have pictures of said contraption you could share?

[Bert Kemp]

I get BB from Woodworkers Source its pretty good most the time but on occasion magnets do the trick. Of course you need a steel honey comb. I'm curious about the bench dog Dave mentioned. Would they have to go all the way thru the hole or do they grip the inside wall somehow. I'm going to look into that.

[Henri Sallinen]

If warping material is a problem, should it be taken into concideration that the sold rulers can also warp and in worst cases, make them unusable for the client?

[Scott Shepherd]

Just a general note, but in some cases it can be bad to pull work down that is bowed because when cutting it, as it cuts through, the work will pop up again, since there's nothing holding it down at that point. It can pop up enough to interfere with your nosecone if you are using a model with the nosecone.

Just be careful. We gave up on it too.

There's all sorts of tricks out there. Taking a spray mister bottle of water, wetting one side, putting granite tiles on it when wet, etc. It's just too much effort for us.

[Keith Upton]

Greg, sorry if I kind of hijacked your thread. Hopefully the info provided to each of us will help both of us out.


I pretty much gave up on thin baltic birch and switched to using acrylic. Less waste and a very good look. I realize you may not have that option.

I do use a lot of acrylic for my other products, but for the Age of Sail game, the wood really fits the theme and the game company wanted to use it for that reason.


Dave,

I have a NdFeB magnet trick that works on the Rabbit aluminium cutting beds, holds just about anything flat including 1/4 warped ply :) I'll ping you an email with the pictures.

cheers

Dave

I'd like to see this as well if you don't mind. colhajj@wingsofwar.org


I buy my Baltic Birch from a fellow Creeker & seldom have an issue with warpage.. unless I lay a sheet in the wrong position for awhile.

Willing to share your source?


Make a slide in fixture that will hold the material flat. Doesn't control what will happen after it is cut but it certainly will keep things flat while cutting

I've got an idea of what you might be talking about, but if you have pics or a diagram you could share that would be great.


If warping material is a problem, should it be taken into concideration that the sold rulers can also warp and in worst cases, make them unusable for the client?

Any badly warped rulers are flattened or not sold if I can't get them flat. But their use in the game does not require them to be 100% flat. They are used to ensure the target ship is in range and withing firing arc (those whitish angles around the ship).

[Bob A Miller]

Well just to chip in here... While I don't cut Baltic birch regularly I went out to my shop & got some smaller but heavier pieces of material (brass & flat steel) I use for weights. I trace my test area & put them down outside it & make the cuts.

Also I tend to break cuts down to slightly smaller sub jobs & not try cutting everything in one go. Allows for changing the weight locations.

Not as elegant as some of the other solutions but it has worked for me. I should also point out I don't run a FT shop so I have the luxury of time.

Bob

[Chad Fitzgerald]

here is what i came up with.280522
two strip of half inch melamine. loosen the screws on the top one, slide the bb under it (i have a shallow rabbit on the underneath so when i slide it in it has a stop to hit) the bottom piece has the slots to make it easy to slide up and down, snug the screws finger tight and go.
works pretty good for me, although like scott said, anything too warped can spring up once cut.

[Greg W Watson]

Awesome :) thanks. It's not warped I get my BB from a member here as well, the slight curve takes the laser slightly out of focus. I have to finish some parts with an exacto knife

[Keith Upton]

Thanks Chad. That looks easy enough to do. I'll have to give that a go.

[David Somers]

Bert,

Don't know if you noticed Mike Null's response about my thought of a bench dog, but he was concerned about the fragility of the material that makes up an aluminum honeycomb? So if you play with this be cautious. There are all sorts of bench dogs. Most fit into their holes by friction, some by an expanding spring or lever, some are a moderately snug fit but as pressure is put on them they cant to one side slightly and that provides the hold.

most people look at a Bench Dog as something that is being pushed against. For example....maybe you have a work bench with a wood vise on it that has built in dogs on it that you can raise up. There would be holes along the bench that you could put regular bench dogs in. You would lay down your wood between the two and close the vice, trapping your stock between the two sets of dogs.

The type I was thinking of has a small arm that arcs across from the post so it can be used as a hold down without any other vice or pressure being applied. Here is a screen shot from Lee Valley tools that shows a variety of bench dogs along with 3 of the "hold down" styles I was referring to. You could make a couple pretty easily that would fit the holes of your honeycomb, but do keep Mike's caution about the delicateness of an aluminum honeycomb in mind as you play with the idea.

Dave

280526280526

[Dave Sheldrake]

280527

Here ya go Keith,

Be aware though NdFeB magnets loose all their power at 130 degrees so having the laser hit them too many times can kill their pulling power (they can in theory catch fire at very high temperature) select the top mag to suit clearance on your aircone (I use 10mm diameter 3mm thick on the top)

The advantage is the power builds the more magnets you stack on the underside so it will hold down just about anything.

cheers

Dave

[Keith Upton]

Thanks Dave. That gives me some ideas on how I might go about that with my Epilog setup. I already have a product that uses these type of magnets, so it should not be to hard to figure out what I would need since I have a bunch laying around.

[Bruce Boone]

On my fiber metal cutting laser, I have an aluminum honeycomb cutting surface, and find that some aluminum ductwork tape works well. It has pretty extreme adhesion, enough to stick my thin plates of titanium down. I assume it should work well for wood as well. It's easy to cut with scissors, and has nice straight edges, so you can grip on about 1/16" at the edge of a plate and hold the plate down pretty firmly.

[Greg W Watson]

280527

Here ya go Keith,

Be aware though NdFeB magnets loose all their power at 130 degrees so having the laser hit them too many times can kill their pulling power (they can in theory catch fire at very high temperature) select the top mag to suit clearance on your aircone (I use 10mm diameter 3mm thick on the top)

The advantage is the power builds the more magnets you stack on the underside so it will hold down just about anything.

cheers

Dave

Dave where are you picking these magnets up from?

Greg

[David Somers]

Greg,

Dave is in the UK so I am guessing his sources wouldn't help you much in Texas. One source for them in the US is KJ Magnetics (kjmagnetics.com). They also have a lot of good information on magnets you might find interesting and useful. The magnets Dave is referring to are the Neodymium magnets, grade 42. There is a stronger grade above that called grade 52. Those might be too strong for this use. Just a guess. I can barely pull those little suckers apart at grade 52.

One caution with these. If you have kids and animals, keep tight control of these magnets. If a child or animal were to swallow 2 or more of these they could do life threatening damage to the stomach and intestines if they pinched tissue in any way. Very dangerous because of their strength.

Dave

[Dave Sheldrake]

Dave's right :)

I get mine from a UK supplier who is local to me (Guys Magnets) in Devizes, Wiltshire.

cheers

Dave

[Mark Sipes]

Is there a disadvantage to double side taping a sheet of .020 sheet steel to the aluminum table bed and using name tag magnets to hold the material down? $10-20 in materials.

[Keith Upton]

Is there a disadvantage to double side taping a sheet of .020 sheet steel to the aluminum table bed and using name tag magnets to hold the material down? $10-20 in materials.

The problem is when vector cutting and splash back on the bottom side. If I'm just engraving, a magnet to the normal table would work.

[Mark Sipes]

Oh I find a sheet or two of news paper (damp with water spray) takes care of any residue from plastic and if you are doing 100's of tags it is a pre-cut separator for shipping.

[James Rambo]

I have some 1/8 inch thick lead sheet. I have cut them into various sizes that can be placed where they are not in engraved areas.
I know of the "danger" of the lead but I limit how much I touch them. Also, today yo can get a lead substitute that will work well.
Why not use some small pieces of steel correctly placed to hold down the ply?