PDA

View Full Version : jigs and fixture tables?



Robert Cowan
02-02-2017, 1:07 PM
I'm looking to cut some holes out of some ABS project enclosures and need some sort of fixture to align them and cut them in batches. I'm wondering what the best way to do this is. I need to stand them up on edge, so there would be a right-angle bracket to hold them. I have a honeycomb table (which is removable), but how do I create a jig that allows me to align the laser so I can repeat the operation for each enclosure? This (http://www.hammondmfg.com/jpeg/1551FLBK_B.jpg) is the enclosure. I would have it on its side, cutting out holes on the side face, so it would be standing up vertically. I can easily make something to hold the part, but I can't figure out the best way to make sure everything is properly aligned. Thoughts?

John Lifer
02-02-2017, 3:59 PM
As always, I'll be smart @@@, I use magnets for a lot of my holding. Also I have a couple of pieces of marble I had screwed up and use it for semi movable placement.
If you are doing a lot, (more than a few) :) I'd probably make something out of MDF or ply that would both hold it up on side and be able to be stable. Shouldn't me very hard to do. make it so the enclosure fits on to it and won't move left/right or up/down.

Robert Cowan
02-02-2017, 4:31 PM
As always, I'll be smart @@@, I use magnets for a lot of my holding. Also I have a couple of pieces of marble I had screwed up and use it for semi movable placement.
If you are doing a lot, (more than a few) :) I'd probably make something out of MDF or ply that would both hold it up on side and be able to be stable. Shouldn't me very hard to do. make it so the enclosure fits on to it and won't move left/right or up/down.

Sure, but how do you accurately reference off of the jig or whatever you're using to hold the piece?

Mike Null
02-02-2017, 5:35 PM
I have to make a couple tonight and I'll be using mdf, wood strips and hot glue.

Scott Shepherd
02-02-2017, 5:42 PM
I have (4) 1-2-3 Blocks. Best thing I ever did when it comes to locating odd jobs. You can bump them against the rulers and it's either 1", 2", or 3" off the ruler, and you can use additional ones to "trap" the part in place. You don't need expensive ones, cheap ones are accurate enough to use. They work fantastic for so many things, especially things that are taller.

Kev Williams
02-02-2017, 7:20 PM
Standing stuff up to run in batches accurately can be tricky, but do-able. Maybe not 20 or 30 at a time, but some's better than one ;)

This is how i'd do it...

I had a machine shop friend make me up a bunch of steel bars a few years ago, a dozen of them are 12" long x 1-3/4" tall x 3/4" thick. I use them for weights to help with warping, I put them against stuff I'm engraving to keep it from moving, and they work for this kind of 'jig' setup--

I drew up the graphic below to show how I'd try to do 15 at once- don't know how big the box is, just guessed at around 3-3/4" long, then drew the bars to scale--

If the boxes are 3.75" long and 1" tall, then overall length of 3 boxes across should be 11.25" --
We have 5 boxes at 1", plus 4 bars at 3/4", so overall height should be 8"...
I'm using 1 bar each on the top and left as stops, so we have to add 3/4" from left and from top--
SO-- top left coordinate should be the zero-corner of the bars, 75" X and .75" Y --
Bottom right coordinate should be 12" X and 8.75" Y.

Now, check the actual coordinates with the red light pointer.

In a perfect world, X will be 12" and Y will be 8.75"...

But if say, X= 12.035" and Y= 8.72", this is what I do... I just put guidelines at those positions. Then, I group all 15 boxes-- then, I'll pull the right side of the group box till it snaps to the 12.035" guideline, then push bottom of the group box up until it snaps to the 8.72" guideline. --part dims may not add up correctly over time because of shrinkage, burrs, etc... doing this puts the parts in Corel where the machine says they are, and now all 15 boxes will be aligned by average. I've found this works well almost always, the only exception would be if you're working with very tight tolerances, say +/- .003". -in which case I would probably only ever do 4 or 6 at time rather than 15...

Anyway, here's graphic, and a photo of my actual steel bars and a similar box I have here, to show the starting point... :)

353066353067


>edit<

I just noticed that with the box's mounting tab "up", then the bottom right corner coordinate should be taken from the top edge of the tab since the red light will actually have something to point at! ;) -- therefore the Y coordinate would be 1" less, or 7.75"...
353068

Doug Griffith
02-03-2017, 7:45 AM
I would build a shallow box using MDF the length and width of the laser's bed, about 1" tall in your case. Both the top and bottom would have holes cut through to index the parts within. Something like Kev's above illustration but holes (or pockets). Building the box with the laser makes it easy to find the origin of each piece.

Kev Williams
02-03-2017, 11:14 AM
I would build a shallow box using MDF the length and width of the laser's bed, about 1" tall in your case. Both the top and bottom would have holes cut through to index the parts within. Something like Kev's above illustration but holes (or pockets). Building the box with the laser makes it easy to find the origin of each piece.
Using the laser to build ANY jig is the best way possible, once you align what you'll be engraving to the jig, provided all the parts are the same, the engraving will always be perfectly aligned :)