Auto-centering pattern help please

[Mike Schwing]

Hi guys. So I don't reinvent the wheel, again, I thought I'd ask for help as someone has run into this before, likely..

I have a pattern made of MDF that I will be using on boards of varying width - just slightly different widths - no more than 1" variance. The pattern is placed on two separate workpieces and then the workpiece is routed to shape. I then need to flip the pattern over and use it on the other workpiece to create the complementary pattern, then join the two together.

If the pattern is not centered exactly on both workpieces, or at least exactly the same, the pieces won't join properly.

I'm thinking that if I can come up with a jig design that will auto-center the pattern on the workpiece I'll be home free. A few hours of thinking so far has gotten me not very far. Your help is appreciated. thanks in advance!

[Randy Schaefer]

Can you find the exact center of the pattern once on each end? You could drill a hole thru these two points on the pattern, making the hole large enough to insert a dowel. Then take a 1X2 or whatever drill a matching hole in the exact center of this board and two more holes an equal distance away from the center hole towards each end. This total distance should be wider than your pattern. Insert a dowel into each of theree holes on the 1X2. Now you should be able to, unless I am waaaay off base here, to use this like a center finding jig. As long as the center dowel is in the center of your pattern when both outside dowels are touching the soon to be shaped board it has to be centered. At least in my mind.

Randy

[Ken Garlock]

but that hasn't stopped me in the past :)

Why not just double-side tape the two pieces together while paying attention to centering the smaller piece on top of the larger one. Then you can make successive router runs, increasing the bit depth each time, until you have cut thru both pieces. Then take the two part and you can have two book-matched pieces, (which I think was your goal?)

Like I say, I probably missed the point of your question. But this only requires a good ruler, and some tape.

[Tom Sweeney]

Not sure if this will work but...

Someone posted a "jig" a while ago -sorry but I forget who.

you could take a piece of MDF or plywood for the base. Then screw two boards at exact 90% angle to each other on top of your MDF or Ply.

Then lets say your work pieces are 6" square or 6" diameter measure from the inside corner of the 90% peices exactly 3" straight out. put a finish nail in that spot & cut off the head with some side cutters.

Then you can slide the workpeice down the two boards and the pin will put a small pin hole in the exact center. If you do the same to your MDF pattern - you can drill a small hole in the center of the mdf and tap a very small finish nail into your peice then slide the pattern over the nail.

Here's a pic of what I mean since I have a hard time explaining it.
Maybe the person with the real centering jig will see this & chime in.

[David LaRue]

but that hasn't stopped me in the past :)

Why not just double-side tape the two pieces together while paying attention to centering the smaller piece on top of the larger one. Then you can make successive router runs, increasing the bit depth each time, until you have cut thru both pieces. Then take the two part and you can have two book-matched pieces, (which I think was your goal?)

Like I say, I probably missed the point of your question. But this only requires a good ruler, and some tape.


Ken,

I was thinking along the same lines, except: Why not just make a complete pattern? ie: Join the two pieces together before roting out the pattern? :confused:

Dave

[Mike Schwing]

Thanks all. Lets go a little further with an explanation.

You may have seen my cutting boards (go to the articles section if not). Most of them have a thin slice cut out of them, it is flipped end for end and then reattached. It has the appearance of interrupting the clean lines of the board with a complementary matching strip.

My idea - I want to make that strip a curve, more like an elongated S, rather than straight.

Here's what I was trying to do. Make a board. Cut it once at 2/3 length (A), then cut a section about 3" long(B), then leave the rest(C). I was hoping to take the 2/3 section, route an S pattern on the end, flip the 3" B section, route the complementary pattern on it, then reattach it. When it was dry, I'd move the pattern over some distance towards the free end of B, which is now glued to A, maybe move it 7/16", and then route the pattern on to that side again. I'd then take piece C, route the same pattern on it, then attach it to B.

I'd then have a perfectly mating S curve embedded into the board - and only you guys would know how the heck it was done.

Can't be done with bent laminations as the S section would already be a glue up of 30 pieces or so.

You'd think I could simply cut the S pattern and use both sides, but the saw kerf removes enough material (even a thin 1/8" bandsaw blade) that the patterns never match up perfectly. I've tried. That is why I figure if I could use the same pattern, just flipped over, it'd be a match.

Any other ideas are certainly welcome! I have a picture in my head of a jig that would serve as a center and a clamping mechanism, I've just got to now go and build it.