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Paul Brinkmeyer
07-29-2011, 7:20 PM
Ok, pin tables are expensive, so I am going to build my own pin table, but thought I would throw out what I was doing to see if anyone can tell if there would be a problem with what I am planning. Or a better way. I am going to make a base out of .5” Corian, but many materials would work. 12 X 24 because it works for me. I will use the laser to mark out a grid of dots 1” apart. And mark dimensions on some of the rows for easy use. Then I will drill holes in a drill press so I get consistency. I do not need to drill all the way though for my plan, but things might change in the future. For the edges I will attach a strip of corian about 2” wide that sits over the edge 1” and above the rulers. Then I can put holes in this for pins that are taller to use as edge stops.
So far so good. But instead of pins for the bed I plan on using marbles or steel balls. I do not know which is better.

With the grid turned on and the spacing set to 1” I can easily see on the design on the screen where I need to put the balls to stay out of the laser path. Total cost should be really low.
Now the questions are, what am I missing? just seems to be too easy.
And how high does the material really need to be above the bed.

Michael Hunter
07-29-2011, 7:48 PM
Drilling all those holes is really REALLY boring!
I know, cos I did over a thousand for my vacuum table with a battery powered drill (used the laser to make a hardboard template).
(Steve/Scott will now pop up and say he can do it in next to no time on his CNC mill).

Will your drill press reach across 6"? Mine will only reach 4.5", so when I do my pin table (I have all the bits, but not the energy) I will make it from 4 smaller bases.

Pins normally seem to be between 1.5 and 2" high (mine are 40mm, but that is just what I could scrounge).

Apart from flashback, I think that you need enough pin height to allow smoke/residue to be sucked out easily from underneath the work.
Corian wont flash back, but you probably want the beam well out of focus when it hits it.

Craig Matheny
07-29-2011, 8:18 PM
" But instead of pins for the bed I plan on using marbles or steel balls. I do not know which is better." Personally I think this is a interesting concept I would not use marbles because they are not created equal the steel would be. Now it the balls could be a product that is real easy to clean it would get better like Teflon coated steel balls. The only concern is the exhaust how to keep the balls from being knocked in or sucked in by those that have the massive systems. Please keep us updated on your progress.

Gary Hair
07-29-2011, 8:23 PM
real easy to clean it would get better like Teflon coated steel balls

You don't want to use teflon, it emits a toxic gas when lasered. The two things specifically mentioned by my laser manufacturer as "NEVER LASER" are teflon and pvc.

Gary

Gary Hair
07-29-2011, 8:25 PM
But instead of pins for the bed I plan on using marbles or steel balls. I do not know which is better.

My vote would be for steel. Marble is laserable and you will end up with the tops of the marbles being different heights after time - not so with steel. I would still go with pins instead of balls, you will still get flashback from the balls but I don't think that's likely from pins. Just my .02

Gary

Ken Shea
07-29-2011, 9:17 PM
What is the usual material for the base on these on commercial units.

Pins seem the way to go to me, what would be the benefit of the balls. you know you are going to have to remove the table for a quick jub on something else, then replace the table to begin again.... bump it coming out or bump it going in, and there they go.

Bruce Clumpner
07-29-2011, 9:34 PM
I'd build in a registration mark in the top corner for an alternate home (0,0). That way, as long as the table is aligned correctly, you can always get aligned back to your origin. Let us see what you put together.

Ed Maloney
07-30-2011, 4:28 PM
Wouldn't the steel balls reflect the laser beam or do I think all steel balls are like pinballs? :cool:

Duane Parcells
07-31-2011, 11:33 AM
I made my pin table out of baltic birch ply coated with paint saturated with as much silica sand as it would hold. The pins.... I use bamboo skewers with the ends soaked in water for an hour before the cutting. Works great. The table is actually a finger box with a center layer to hold all the "pins" vertical. The longer you make the pins the less beating the box takes. Boxes are 12 by 24. 3 of them makes up the 24 by 36 of my laser.

Duane

Joe De Medeiros
07-31-2011, 11:16 PM
I remember reading about someone using pop revits as pins, try doing a search on the form.

Paul Brinkmeyer
08-01-2011, 12:08 PM
Good ideas.
Ran a few tests over the weekend using about a ½ inch ball, and Steel balls are out. At least the really shinny SS ones. If the beam hits the ball close to the top, it does mark the bottom of the material. Even as my plan is to arrange the balls so the beam never hits a ball, I know stuff happens. That, and the ball does have a rather large target area on top, making missing the ball even harder. I think any ball is out at this time.
So now I will look for a pin. I like the idea of pop rivets, but the pop rivets I have found vary in height too much.
I will be looking for a common pin that local hardware stores carry to keep costs down first, and it has to be easy to put in the plate move, or take out.
BTW, If the ball concept would have worked, my total cost would have been $10.50.
Duane, I’d like to know about the skewers? How do they really hold up after the beam hits them a few times?

Rodne Gold
08-01-2011, 12:12 PM
Why do you actually need a pin table?

Michael Kowalczyk
08-01-2011, 12:19 PM
Clean up will be a bugger if you have small parts that will fall through. Also sometimes you need to have support under parts so they don't fall partially and end up on an angle and can interfere with the laser path. Sometimes when a part falls it may fall into the lower path of the next part to be cut and get scorched by the laser. You have to clean it regularly otherwise fallen parts may catch fire and scorch your material.

Problem with rivots is unless you have the hole tight enough for a slight pressure fit, when you raster the material may move from the motion.

Acrylic is a fair to good temporary base but if you use it a lot you will have to replace it. Curious to see if after you have done a few days of laser work, if the base will remain flat or will it start to warp.

I am also in the process of building one that solves these problems.

Paul Brinkmeyer
08-01-2011, 12:39 PM
Clean-up is one reason I wanted to go shalow dimple. Nothing falls through the table, easy to clean-up.
Do you think 1/2 inch corian will warp?
I guess if it does, the other issue would be how fast?
Corian is replacable.
what are you using for a pin?

Paul Brinkmeyer
08-01-2011, 12:46 PM
Why do you actually need a pin table?

I do ornaments, and I get reflection from the table, making cleanup time consuming. I have noticed the cutting BB is cleaner when supported this way too.
Currently I use scraps of material to space the material 1/4 inch off the table and all is well. But I have to making sure I do not hit a spacer.
That is why I want to build a pin table that has pins easy to move and locate, just using the same grid I use in CD already.
I am oopen for other ideas. Taping works, but I really do not want to tape everything if I do not have too.

Michael Kowalczyk
08-01-2011, 1:27 PM
Clean-up is one reason I wanted to go shalow dimple. Nothing falls through the table, easy to clean-up.
Do you think 1/2 inch corian will warp?
I guess if it does, the other issue would be how fast?
Corian is replacable.
what are you using for a pin?
Hey Paul,
Most of the parts I cut will have small parts that drop through and are a pain to clean with big fingers. vacuum won't work, can't blow them off because then all the pins come out. Pins should not be able to wobble.

Corian as with any acrylic material is replaceable but the labor to machine it is not without additional costs. depends on what your volume is and what you want to spend your time doing. lasering and making money or building pin tables that cost you time money?

I am experimenting with a few different types and have ruled out the pop rivets for now. Too costly to have pins machined out of aluminum, HDPE or delrin. Acrylic pins are too fragile. I have gone through macmasters, graingers and many other vendors but have not found the ONE that will work and be cost effective. Since my table is a little over 28x16 it can hold 432 pins and even at .50 cents each that adds up quickly. Sure rivets are cheap but they don't solve all the issues and create others.

So I have a smörgåsbord of parts I am trying but I can't let the cat out of the bag quite yet, since I may bring it to market, but will help where I can.

Martin Boekers
08-01-2011, 1:50 PM
[QUOTE=Michael Hunter;1750146]Drilling all those holes is really REALLY boring!
.QUOTE]

I think I would find someone locally with a CNC Mach. and trade off some laser work work for them drilling
the holes. Just a thought.

Paul Brinkmeyer
08-01-2011, 2:05 PM
Martin, The only local person with a CNC that I have found does not believe in do that.
Nuf said about him.

Michael,
agree on steady pins.
do you plan on having all the pins in all the time?

I was thinking of only putting pins in the locations needed, if the support foor both the fall off and finished product is needed, I just add pins to the fewest locations I have to so access to "things" falling to the table are reachable. For the items I have planned, picking up big parts is easy, and most of the falloff is vacumable.

Maybe I need to change what I am thinking. I was planning on a 1" grid.

Mark Ross
08-01-2011, 2:33 PM
Why do you actually need a pin table?

The stuff we cut ends up gumming up our vector grid over time (3 months) and then we get that whole fire issue. Plus the cost of vector grids. We have tried a peg board and printing up support pins on a 3d printer, but when the laser does go over them...fire and smoke and char on the underside of the material we are cutting. We could set up the jobs so they put the pins in to miss this, but with how many jobs and how often we switch over every day it would be a royal pain. Aha! I just had a thought. Pegboard is cheap and printing up pins is relatively inexpensive...maybe i make dedicated pin tables for our high volume always changing over job and the low volume stuff, I leave on the vector grid for now...hmmm...I have to go "play" around now...

Rodne Gold
08-01-2011, 2:53 PM
how about golf ball tees - they should be cheap and all uniform..I still don't understand why a pin table is needed, we make awards etc where finishes are paramount , mostly we just elevate sheets of whatever we cut, unless real small parts (honeycomb for those), with 1/2" blocks of acrylic , no flashback , no melt problems , no fume evacution problems , no fires ..... been doing it for 12 years+ as well as using honeycomb for that period on multiple lasers with none of the hassles you guys seem to have? BTW we use a sheet of black anodised aluminium on top of the stock table and under the honeycomb and acrylic blocks , it acts as a sort of "stop" for the beam , noi reflection at all off it.

Paul Brinkmeyer
08-01-2011, 3:39 PM
Rodne,
That is what I do now, blocks of acrylic under the sheet, but every sheet I cut is different so I am always moving the blocks and figuring out where to put them. Many times I do not have room for a block, or miss judge where to put the block and cut over it. This leads back to cleaning.
Most of my parts are small. A table with removable pins on a grid would make setting this up easier as CD can show a grid and find the points to take pins out.
Don't you get flashback when you cut smaller parts right on the honeycomb?
Or is your honeycomb table different/better as far as flashback is concerned?

Glen Monaghan
08-01-2011, 4:29 PM
I use a pin table made from 12"x24" MDF. I used the laser engraver to mark the pin locations on half inch centers starting at an odd distance from the edges (to minimize the likelihood of lasering over a pin) and took the time to drill all the holes on a large drill press. Using the press kept all holes vertical and the press's stop collar ensured uniform depth.

For pins, I bought an inexpensive package of headless brads for a nail gun. The brads are glued together side-by-side into a strip that are supposed to be loaded into the nailer (vaguely similar to the way staples are glued together and loaded as a strip into a stapler). Since the tops of the brads were flat, I opted to use a dremel and grind both sides of the brad strips to quickly give each brad a wedge or chisel tip so there is essentially no reflection or flashback if the laser ever hits a pin.

I swapped pins in and out a time or two for specific jobs, but eventually found it too time consuming and unnecessary. Then I used a pin in every hole for a while, but found it unwieldy to remove bits and pieces that managed to fall between the closely spaced pins. Now I usually just keep pins in every other hole (1" centers), offset one hole on alternate rows/columns to form a diamond pattern, and only temporarily add a few pins where needed for rare situations that need more support for small cutouts.

Works for my purposes.

-Glen

Craig Matheny
08-01-2011, 4:49 PM
I do ornaments, and I get reflection from the table, making cleanup time consuming. I have noticed the cutting BB is cleaner when supported this way too.

I was doing something like this that I needed to raise the wood so on the sheet that the art was on I put holes where I wanted the pins cut the sheet saved it erased the holes in the master file this became the jig I would set this on my honeycomb table and put #10 screws in the location of the holes and done worked great if you do not need a ton of pins I did about 8 for a 12 x 24 sheet

Glen Monaghan
08-01-2011, 6:48 PM
So now I will look for a pin. [...]
I will be looking for a common pin that local hardware stores carry to keep costs down first, and it has to be easy to put in the plate move, or take out.
BTW, If the ball concept would have worked, my total cost would have been $10.50.


See my note from earlier today regarding brads or pins for small nail guns. A pack of 1000 is only $3 or $4 plus tax and you can get them in your choice of lengths from about .75" to 2".

-Glen

Duane Parcells
08-01-2011, 7:40 PM
The bamboo skewers are disposable. I buy packs of hundreds and lay them on the vector table and cut them to length with the laser (use tape to hold them together during cutting). Soaking them in water helps keep flaming up to a minimum.
I do inlays that have several hundred pieces. If you cut from the bottom (another subject well covered in other threads) on the vector table the tick marks are a real pain to sand out of small pieces. The pin table is well worth the time and effort to build
if you cut from the bottom and is a much better way to cut to begin with. I also tried bullets (Sharp points, no, not live rounds) in the beginning, They are very uniform in size, works well but had the same problems that the steel balls had.

Duane

Zvi Grinberg
08-02-2011, 1:55 AM
Why not just use thumb tacks?
What could be more affordable, painless to replace, randomally spread at any density and field size?

This is the first picture I found, but you can easily find it in bare metal (and cheaper) style.

203831

Mike Null
08-02-2011, 6:40 AM
If you're going to use thumbtacks why not use pushpins.

Glen Monaghan
08-02-2011, 8:01 AM
If you're going to use thumbtacks why not use pushpins.
Center of gravity would probably be high enough and base narrow enough with pushpins that they'd tend to be unstable and want to fall over with little provocation while placing objects on top of them. Lower CG and wider base might make thumbtacks usable, although they may be a bit on the short side.

-Glen

Michael Kowalczyk
08-02-2011, 1:04 PM
I bought a bunch of magnetic push pin style pins and they worked OK for a while but the plastics melts and causes ridges fairly quick if they are in the path.

http://www.magnet4less.com/product_info.php?products_id=287

Still not tall enough to prevent flashback but will get you by in a pinch. Not sure how the thumbtacks would work. Nothing holding them in place, can scratch or stick to bottom side of material or get sucked up in fume ventilation. Curious to see if anyone attempts using them with successful results. I think the only way you would not have flashback is to dial back your power but then you risk the possibility of not cutting all the way through and slowing down production. So you will have to ask yourself "Is the juice worth the squeeze"

I am experimenting with pins about 1.5" or about 40mm. I believe it is high enough to prevent flashback and will still be stable once we finish the pin to grid mounting system we are developing.

These brainstorming sessions always produce something.:confused:

Hopefully something usable;)

Michael Hunter
08-02-2011, 2:19 PM
I scrounged things called "dowel pins" (used by mechanical engineers).
They are ground to a precise diameter, so if I get the hole size right they should not jam or wobble.
The ends are slightly domed, so they won't scratch the work and the length is very uniform.
Not the cheapest solution if you can't scrounge them, but won't break the bank either.

It seems to me that using anything with a sharp point defeats the object - you just swap flashback for scratches and the work is still spoilt.

Michael Kowalczyk
08-02-2011, 5:11 PM
Ok, pin tables are expensive,.

Hey Paul,
We got so busy with the design side that we missed the 1st part. What do you, or others, consider to be expensive? Let's use a 12" x 24" base, as you mentioned in your OP, as the standard to use for pricing a unit.

I know Epilog makes a 12"x12" and you can get 2 to make a 12"x24" but last time I checked they were like 395.00 each plus shipping. So that would bring it to at least $800.00+USD. Universal just came out with one that is 12"x12" with 16 pins and 4 guide pins for 325.00 each. So that's around 700.00 +- with shipping.

I bought a pin table, from Europe, for around 400.00 but it was 17"x29" and came with 80pins but I requested more. They have a 12"x25" with 50 pins for a little over 300.00. But the pins are very loose/wobbly and too short, aluminum base is not truly anodized and the business owner is very difficult to deal with and could not get refund without paying 750.00 in international shipping charges and customs. So I am stuck with an incorrectly machined block of aluminum and several 100 pins that all wobble. Maybe my expectations are high but a machine shop that supposedly does this all the time should be able to make them fit without wobbling and be taller and do it in less than 5 months.

Sorry for the nano-rant but just wanted to show that I have tried several methods and have tried a few that are currently on the market but none of them can do, what I want it to do or will be able to do, what the one I am working on will be able to do, for a reasonable price.

Ross Moshinsky
08-02-2011, 5:36 PM
I'm not sure why this is complicated for everyone.

McMaster sells pins for next to nothing. We use .125"x1.5" pins PN: 98381A478. They are definitely accurate enough for a pin table. Then just take a piece of material and drill a bunch of holes. We used a thick piece of acrylic but something like Corian would work as well. It's not complicated. If you're concerned about marking your base material, just use taller pins.

Robert Walters
08-02-2011, 6:48 PM
Question...

What kind of spacing between rows and columns of pins are you looking at?

Is it a H/V grid?



+ + + +
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+ + + +


Offset grid every other row?


+ + + +
+ + + +
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How close to the edges of the base?

If you want the pins to be "snug", how snug?
Usually inserting/removing them over time would open the holes I'd think.

Ross Moshinsky
08-02-2011, 8:06 PM
We did H/V with .25" spacing but honestly I don't think it will matter one way or another. Just save the file when you're done and use it as a template for laying out your parts. That way you can figure out exactly where you need the pins.

As for snug, we marked the holes on our big rotary engraver and then drilled the holes with a drill press. They are snug as the pins from McMaster are pretty darn accurate in their sizing. Will they get looser over time? Sure, but for them to get loose enough where it becomes unusable would take a good bit of time. I'm guessing years but if you use it all the time, even if it needs to be replaced annually, you're looking at an investment of a half a day at most and an annual investment of less than $20. Not really a big deal.

Paul Brinkmeyer
08-03-2011, 12:10 PM
I got some brads from the local hardware store, and found a 0.065" dif in length. Just a little too much. Plus I would not know how reliable it would be if I needed more, and got some from a different batch or vender.

As far as cost.....lets just say the purchase of a pre-built fails in two ways.
1. Price is just too high for what I have found so far. I really do not have a target cost, but it should be somewhat less than the prices I have seen to date. If I could use say the steel balls, my total cost for parts would have been under $15.00. As it is for my own use and I have the time, drilling the holes might take some time, but will not stop me from selling anything.
2. I am trying to make something easy to clean or replace.

And I was hoping to use all local supplies. I might have to breakdown and order off of the internet.
Plus I do not have much shop equipment, so if my "spacer or pin" does not gauge off of the top of the plate, I will need to drill all the way through and stop off of the bottom by adding another layer of something under the corian for the pin to sit on. In other words, I can not stop my drill press at a certain depth repeatedly.

some great ideas out here.
And I am still trying different things. Today I hope to work on what height pin I want.

Glen Monaghan
08-03-2011, 1:08 PM
I got some brads from the local hardware store, and found a 0.065" dif in length. Just a little too much. Plus I would not know how reliable it would be if I needed more, and got some from a different batch or vender.


Sounds like you bought loose, individual brads??? You need the flat, headless brads that are glued together in strips for nail guns. I just checked the ones I have and generally was seeing no more than 0.001-0.002" variance in length, with a maximum that I found of 0.004". I bought a couple of packages of 1000 each for something like $3 or $4 each, so probably a lifetime supply for my pin table.

-Glen

Mike Mackenzie
08-03-2011, 1:19 PM
Here's another suggestion that is easy and in-expensive. This really only works for larger cutting ie pieces over one inch.For the larger parts what I do is use my cutting table and some 1/4 lag bolts. The 1/4 is the same diameter as the honeycomb cells and you just put them where you want them. It is a little bit of a hassle to get them in the area that you want but they work well and are easy and cheap. Once you set it up then you can run what you need.

I also remove the original adhesive and if necessary re-mask with the lo tack application paper.

Like I said this works well with larger cut outs will not work very well with small cuts this also will work as a location fixture when you get odd shapes that you need to do use the lag bolts in the cutting table to reference from as seen in picture 3.




204000204001204002

Paul Brinkmeyer
08-03-2011, 1:34 PM
Glen, yes I bought loose brads.
To get brads for a nail gun it I will have to drive to the BigBox store. This is not longer local for me.
I do not go there very much, but next time I get close to one I will look.
Thanks

Mike, I have done similar things, and will continue to.
But I am still will look into building a pin table.
Thanks

Bruce Larson
08-03-2011, 5:05 PM
Here is a totally different way to solve these problems. I cut and form bent aluminum thin sheet metal channels in many different lengths and widths, but the ones I use most of the time have about 3/4" high legs and are 1.5" wide and 12" long. Then I just place them with the legs facing upwards randomly under whatever I am cutting to have enough support for the parts. Small pieces just fall thru and have not been a problem. Occasionally, some medium small parts will tip up after cutting, but pushing stop and removing, then resumeing usually gets most everything. If I need to have an exact edge distance on the sheet, I use double sticky tape on two 1x1x3 wood blocks stuck to the top and edge rulers to set zero. Some small parts will fall thru and get re-cut or damaged, but if they are that small it is easier to just cut extras as you can't be worried about spending that much, and will save far more in labor. Oh, we tried the honeycomb, pins, small blocks, etc. but have been using this method for 5 years or so and it has been very effective. Simple and cheap.

Michael Kowalczyk
08-03-2011, 7:17 PM
Hey Bruce,
Beautiful area you are in. It's been a few years since I was over there, Schlitterbahn and some resort hotel for a Thermwood training, and hopefully can get back again soon.

You know the old saying..." A picture is worth a 1000 words". save your fingers and send us 3-4000 worth of pics;) of what you explained above.

Thanks and ...

Bruce Larson
08-04-2011, 3:25 PM
OK, here are two photos to illustrate. These particular channels have been in use for over two years, and you can see that a couple have had some HOT events, but nothing catastrophic. Ihad previuos prblems with honeycomb table getting flashback on acrylic at many of the comb joints. Here the only time the laser passes over a joint, it is only for a very small time and leaves no marks.204114204115

Michael Kowalczyk
08-04-2011, 5:10 PM
Hey Bruce,
Thanks for the pics. That may work for large parts but might be an issue with the variety of small parts we do and they may hang up when they fall down or get in the laser path and get scortched. The way you have them currently positioned , IMHO, would inhibit much of the airflow from freely circulationing under the material. There is more than one way to tie a shoe and it sounds like this way works for you. Thanks for sharing.

How many watts is your laser? What kind of material are you cutting and how thick is it?

Bruce Larson
08-04-2011, 7:12 PM
60 watt epilog, 1/8" to 1/2" acrylic.

Rich Harman
08-13-2011, 1:50 AM
Here is my answer to the pin table. This was only a test piece, a first iteration of something fancier. It works well enough that for now, I can't justify spending more time on it.

The 3-1/2" 16 penny finish nails are pressed into the holes one by one, the holes are sized so that the nail fits very snugly but not so tight that it has to be hammered. Once all of them are most of the way inserted I place it on the concrete floor and use a length of PVC pipe to press the 6mm MDF all the way down.

The heads of the finish nails are spaced so that they fit into the honeycomb, it does't slide around. The nails are long enough that the laser leaves no marks on the MDF.

204928204929

lee chitwood
09-14-2011, 5:02 PM
207594207595207596
Actually, I made a pin table using 3 laminated layers of 1/4" baltic birch ply with 3m PSA sheet on 2. Laid them out on CD, 1" o.c., 1/2" from left stagggerede. For the pins I used 3 inch Ram-set nails w/head cut off with a 4" grinder w/cut-off wheel. I bundled with an appropriate size hose clamp to hold them all at once while I ground them the same size on the former head end using a belt sander. All pins same length...very important. I miked the nails for the hole size for CD layout. I then cut all holes....alot (276)x3 layers. I keep a layout file colored with something the laser won't recognize, semi-transparent and paste over the pieces i want to cut in CD to locate the pins as required.

Larry Allred
09-18-2011, 2:45 AM
I did my pin table with 1/4 clear acrylic and pop rivets. I laid out the plate in Corel, had the laser drill all the holes. Rivets have a sleeve and shoulder that goes down the hole leaving the long thin end pointing up. Use long rivets to keep some of the heat off the plate. And raise the plate up with feet.

You want tiny points of contact and very little width in the pins (same principle as the grid) to reduce burnback. Steel or aluminum pins will hold their shape better than wood, bamboo, anything else. Also need to make sure the pins are close enough to support the pieces you're cutting, otherwise they'll tip or fall and get secondary burns. Balls might seem like a good idea, but there's too much area there under the project and defeats the purpose of a pin table.

If you do plenty of evenly spaced holes you can drop rivets in wherever you need them for any project. Also take a couple of steel "L"'s or long corner shapes to make a left and top edge, and glue the feet so they line those edges up to the rulers. 1 piece of plastic, a couple boxes of rivets and some time can get you a nice pin table without spending up the wazoo for a factory one.

Dennis Rech
09-18-2011, 6:08 PM
When I needed a quick pin table, I covered a 3/4 inch piece of 9x14 mdf with two layers of aluminum foil (prevents burning the mdf) and used 1-1/2 inch finish brads pounded into the mdf 3/4 inches. I hot glued a pair of 3/4 inch high aluminum blocks to a set of pliers to hold the brads while I pounded them into the mdf. The blocks assured that the brads would stick out of the mdf exactly 3/4 inches.
Open the pliers after pounding, insert another brad and give it a tap. The whole thing took about 15 minutes and a box of brads.
With the aluminum foil to protect the base, one could likely use a base piece of Styrofoam with good results.
Dennis

paul mott
09-19-2011, 4:37 AM
When I needed a quick pin table, I covered a 3/4 inch piece of 9x14 mdf with two layers of aluminum foil (prevents burning the mdf) and used 1-1/2 inch finish brads pounded into the mdf 3/4 inches. I hot glued a pair of 3/4 inch high aluminum blocks to a set of pliers to hold the brads while I pounded them into the mdf. The blocks assured that the brads would stick out of the mdf exactly 3/4 inches.
Open the pliers after pounding, insert another brad and give it a tap. The whole thing took about 15 minutes and a box of brads.
With the aluminum foil to protect the base, one could likely use a base piece of Styrofoam with good results.
Dennis

I think the flash backs from that foil (3/4" away) would certainly mark the underside of some items that you cut Dennis. :)

Paul.

Michael Kowalczyk
09-19-2011, 6:04 PM
My testing shows that under an inch is not enough distance to keep flashback to an absolute ZERO. Around 1.25" to 1.5" is the optimum so far for me when using an aluminum foundation.

An acrylic foundation like Corian, other solid surface materials or just plain clear 3/8 to 1/2" acrylic will not flashback but the board will deteriorate quicker over time and most likely not stay flat as your laser heats it up on one side.

Dennis Rech
09-20-2011, 12:09 AM
I think the flash backs from that foil (3/4" away) would certainly mark the underside of some items that you cut Dennis. :)

Paul.

It's no problem at all.
The laser is a FSE 40 watt with a 2 inch lens. There isn't a lot of energy left (10% power and 100 percent speed) after burning through the cardboard above and with the short lens, the beam diffuses pretty quickly and diffuses even move on the bounced return. The FSE only has about 4 inches of total z height, so longer nails are out of the question.
I made the pin table because I was getting smoke marks from the honeycomb table. The pin table gave a lot more ventilation.
The important part of this is the use of the block gauges to assure uniform nail height which assures even cutting.
Dennis

Michael Kowalczyk
09-20-2011, 3:00 PM
Yes I can see why it works for you. 2" lens gives you an extra half inch ( I use a 1 1/2") and using only 10% power of a 40 watt, when I use 100% of a 60 watt.