Enlarging a template by exactly the size of the cutter-bushing gap? - Page 3 - Router Forums
 3Likes
Reply
 
LinkBack Thread Tools Display Modes
post #21 of 45 (permalink) Old 09-16-2019, 01:28 AM Thread Starter
Registered User
 
Join Date: Nov 2017
Country: United States
First Name: Ashley
Posts: 68
 
Default

For those trying to picture what I'm doing, look at any of these...
First 30 seconds of
First 20 seconds of
First 30 seconds of

None of them are exactly what I'm making... but all of them illustrate the grid of holes I need to create.

@tomp913, I'm familiar with the parf guide system, and it definitely could work, but I've been looking for a router based solution.

@Biagio, are you talking about these? Dog Hole Bushings and Bits - Lee Valley Tools

After the suggestions here yesterday and a night of working on the project in my dreams, I have at least half a dozen alternate approaches I wasn't seriously considering previously... some of which dodge the hole enlargement problem. And, between that and the comments above, I'm reconsidering drill based options too. Let's see what another night of attempted sleep brings.

-Ashley
AshleyJ is offline  
Sponsored Links
Advertisement
 
post #22 of 45 (permalink) Old 09-16-2019, 10:04 AM Thread Starter
Registered User
 
Join Date: Nov 2017
Country: United States
First Name: Ashley
Posts: 68
 
Default

The woodpeckers template system that gmedwards referenced is almost exactly what I was trying to create.

I say was because Iím also considering a couple other alternatives now, but that approach is definitely still open. Iím holding back from bringing all those alternatives in here because they donít really fit the template theme of this forum... but I may yet do so.

I do strongly resonate with joatís preference to make a template rather than buying one. This isnít only a matter of price as I could easily spend at least half that price hunting down the metric rabbet/bearing combinations and other things I need.

***This is very much about the challenge of bootstrapping a reasonably precise solution without a lot of fancy/expensive tools.***

So, having an original with the exact hole size and spacing required, enlarging those holes with a rabbet bit followed by flush trim was an appealing solution. However, the three piece challenge of a rabbet that enlarges by exactly the amount that a bushing + cutter reduces is proving more difficult than I anticipated. I originally asked because I canít imagine this problem hasnít been solved before. I thought someone might say... ďYes, use a size X rabbet from vendorX with bushing size Y from vendorY with spiral upcut Z from vendorZ... thatís how I do all my original to template resizing transitions.Ē

But since the woodpeckers template gmedwards pointed out, and joatís preference for making his own *do* fit with the template theme of this forum, Iíll expand to ask a different question...

...How would you DIY a template like that if precision was critical? Say you need to keep the spacing error of the grid under ten thousandths of an inch max... whatís the simplest way you can think to create such a template? (Iím not asking in the CNC area because thatís the obvious answer!)




Sent from my iPad using Tapatalk

-Ashley
AshleyJ is offline  
post #23 of 45 (permalink) Old 09-16-2019, 10:12 AM Thread Starter
Registered User
 
Join Date: Nov 2017
Country: United States
First Name: Ashley
Posts: 68
 
Default

BTW, my current sidetrack is determining whether big box pegboard is consistent enough to be used as a reference to create such a template and keep the hole spacing error within a few thousands of an inch.



Sent from my iPad using Tapatalk

-Ashley
AshleyJ is offline  
Sponsored Links
Advertisement
 
post #24 of 45 (permalink) Old 09-16-2019, 11:08 AM
Moderation Team
 
Cherryville Chuck's Avatar
 
Join Date: Sep 2010
Country: Canada
First Name: Charles
Posts: 15,267
 
Default

The pegboard is consistent. The way I drilled my bench holes was by taking a block of wood like in the Lee Valley link and drilling a hole through it on the drill press to make sure it was 90* Then I just marked out the holes with a pencil and tape (they really don't need to be all that accurate for bench dogs) and I drilled the first 1/8" by hand so that I could stick the bit in it and know I was in the right spot once the block of wood was over it and I couldn't see it anymore. I drilled as far as I could with the block and then pulled the drill bit out and carried on by hand (4" think bench top). No issues. Yes the block of wood guide wears faster without the guide but not enough to worry about doing one work bench.

If you are really fussy about getting the holes even then build a "leap frog" type drill jig. That's where you drill two holes in the wood block and you put a second drill bit or steel rod through one hole in the block and into the last hole you drilled and use the second hole in the block to drill the next hole. The distance between the holes in the block never changes so the spacing pattern of the drilled holes also stays the same. If you decide to go that way I'll describe and easy way to make it.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
Cherryville Chuck is online now  
post #25 of 45 (permalink) Old 09-16-2019, 01:09 PM Thread Starter
Registered User
 
Join Date: Nov 2017
Country: United States
First Name: Ashley
Posts: 68
 
Default

Chuck, yes I am very fussy about getting the holes perfect, since I hope to use them as references for keeping things straight and square. Your description made perfect sense... thank you! The leapfrog technique to guarantee exact hole spacing is clear, and I see how to do that with either a drill or router jig. (I still prefer router, in part because it simplifies keeping things vertical, but either could work and I may reconsider.)

The leapfrog technique will guarantee hole spacing in a single dimension (ie line). The challenge is getting it perfect in two dimensions, ie identical spacing in both X and Y dimensions, and ensuring those dimensions are exactly perpendicular. Your answer that pegboard is consistent means that it's probably the simplest reference. If you have another way to get consistency in both dimensions and ensure they're square, then I'm all ears.

I'm thinking of a pegboard based an approach like the following... and any improvements are welcome...
  1. Acquire a piece of 3/8" clear acrylic, say 12" x 12", to make a new router sub-base.
  2. Acquire pegboard. Cut a smaller piece sized to match the new router base.
  3. Acquire some metal rod or bolts that snugly match the pegboard holes. (That's 1/4" diameter for the pegboard linked above, but some pegboard has smaller holes.) From this rod, cut four pins that are 1/4" longer than the pegboard holes are deep.
  4. Clamp the acrylic to the piece of pegboard. Using the pegboard for precise alignment, drill four holes 1/4" deep into the acrylic in a square pattern, say 4" on a side. Drill a fifth hole at the center of that square, this time penetrating all the way through the acrylic. Use the drill bit to perfectly align to the pegboard holes, so the resulting holes in the acrylic perfectly match the pegboard.
  5. Remove the acrylic from the pegboard.
  6. Position the acrylic on the router base with the four holes in a square facing away from the router. Use either a centering cone, or a bit precisely matching the center hole, to align the new sub-base to the router. Once alignment is perfect, use the router base as a template to mark holes to mount the new base to the router. Drill and countersink those mounting holes.
  7. Install a pin in each of the four remaining holes. These are the pins from step 1, which precisely match the pegboard holes.
  8. Install the plate on the router with pins facing down.
  9. Cut a larger piece of pegboard, matching the size of the workpiece to be drilled, and clamp it atop the workpiece.
  10. Mark every 4th hole on the pegboard in each dimension (4th hole for 4" spacing), as these are the holes the router base pins should align to for drilling all the required holes.
  11. Install the desired router bit (plunge capable 20mm or 3/4"), and start making a mess.

Other thoughts...
  • In step 10, I'll probably fill unnecessary holes with woodfiller or bondo to eliminating error opportunities.
  • In step 4, it's easy to drill additional alignment holes other than that 4" square, but I'm not thinking of any reason that it will ever be needed when used with pegboard as described in steps 9-10.
  • In step 7, the pins can easily be secured with a drop of epoxy. However, I'd prefer removable pins so the base is useful for other routing operations. I may see if they're snug enough for a press fit to work.
  • Another solution for removable pins is to thread the end of the rod and tap the hole in the acrylic. Not owning a tap & die set and lacking experience with one, maybe I'll skip it and let this be a special purpose base. Or maybe it's time to learn?
  • Alignment of the router mounting holes in step 6 is quite critical. My explanation of that procedure is lacking, but more robust explanation can be found in this thread.
  • Alignment of the router mounting holes in step 6 is actually not critical IF the new sub-base is always used in the same alignment. If the sub-base is rotated, then I'll incur an error matching any error in centering the sub-base. For this reason it makes sense to avoid rotation.
  • I expect the pegboard to be reusable many times before it's holes wear too much to precisely position the sub-base with pins. I may drill out the pegboard only first (step 11) before using it with a workpiece, to make it easier to position it exactly as desired.
  • A similar procedure could be used to make a base for a drill guide based on either Chuck's block of wood or the Lee Valley bushing. Such a base would allow the drill guide to reference pegboard for exact spacing in the final pattern of drilled holes.
  • If I want to end up with a template like the woodpeckers one, which uses a bushing guided bit instead of a bit the full size of the target hole... then the above procedure with pegboard can produce that template... as long as I use the bit size needed for the final template hole rather than the original hole... otherwise I end up where I started this thread, needing to enlarge the original to be a viable template.

-Ashley
AshleyJ is offline  
post #26 of 45 (permalink) Old 09-16-2019, 01:16 PM
Forum Contributor
 
Stick486's Avatar
 
Join Date: Jan 2013
Country: United States
First Name: Stick
Posts: 25,552
 
Default

Drill Guide - Lee Valley Tools

This would have been the week that I'd have finished chewing thru the restraints...
If only new layers hadn't been added....

Stick....
Forget the primal scream, just ROAR!!!
"SNORK Mountain Congressional Library and TaxidermyĒ
Stick486 is offline  
post #27 of 45 (permalink) Old 09-16-2019, 03:13 PM Thread Starter
Registered User
 
Join Date: Nov 2017
Country: United States
First Name: Ashley
Posts: 68
 
Default

I just found this video of someone using pegboard exactly the way I envisioned:

If the repetition doesn't put you to sleep right away, you'll see him make positioning errors in a couple places. This convinces me that filling unnecessary holes with woodfiller or bondo is a very good idea.

-Ashley
AshleyJ is offline  
post #28 of 45 (permalink) Old 09-16-2019, 05:01 PM
Forum Contributor
 
Stick486's Avatar
 
Join Date: Jan 2013
Country: United States
First Name: Stick
Posts: 25,552
 
Default

Quote:
Originally Posted by AshleyJ View Post
I just found this video of someone using pegboard exactly the way I envisioned: https://youtu.be/TuPC7aVYpmk

If the repetition doesn't put you to sleep right away, you'll see him make positioning errors in a couple places. This convinces me that filling unnecessary holes with woodfiller or bondo is a very good idea.
Tape over what you don't want...
you may change your mind later..

This would have been the week that I'd have finished chewing thru the restraints...
If only new layers hadn't been added....

Stick....
Forget the primal scream, just ROAR!!!
"SNORK Mountain Congressional Library and TaxidermyĒ
Stick486 is offline  
post #29 of 45 (permalink) Old 09-16-2019, 05:05 PM Thread Starter
Registered User
 
Join Date: Nov 2017
Country: United States
First Name: Ashley
Posts: 68
 
Default

Thanks for suggesting tape, Stick. That's much easier and faster.

Back to the big picture, I finally figured out the puzzle that's been haunting me... a router centric solution that works even if pegboard spacing wasn't perfect...
  1. Make a custom router sub-base and attach to the bottom of it a length of miter-slot-rail 3/4" wide x 3/8" deep. The chosen spacing from the rail to the bit will ultimately determine the spacing of holes, in my case either 4" or 96mm (not sure yet).
  2. Put a 3/4" dado or mortising bit in the router and attach the custom base to the router.
  3. Get a piece of material to use for a jig, 3/4" thick, and as big as you want the jig to be. Ensure the jig stock is square, as it's squareness is the reference to square the grid of holes.
  4. Running the miter-slot-rail of the against one edge of the jig stock, cut a dado in the jig stock. The final depth must be slightly greater than the depth of the miter-slot-rail (3/8").
  5. Running the miter-slot-rail in the just completed dado, cut another dado parallel to the first. Repeat this procedure until the entire jig stock is covered with parallel and perfectly spaced dados.
  6. Repeat steps 4 and 5, but referencing from a perpendicular edge of the jig stock. The result will be a grid of perfectly spaced dados all over the stock.
  7. Mount a second miter-slot-rail on the router base, perpendicular to the first and spaced from the bit the same distance as the first. To do this, place the first rail against the first referenced edge of the workpiece and align the bit to the first perpendicular dado created in step 6. Now the second miter-slot-rail may be positioned against the edge of the jig, and clamped to the base. Test to confirm spacing perfectly matches the bit to both dados, then drilled through the base and rail for mounting screws.
  8. The custom sub-base with two perpendicular miter bars can be used to accurately position the router at each dado intersection in the jig stock. Mount the desired router bit for dog holes (3/4" or 20mm), and plunge the bit to bore the required holes referenced from each dado intersection.
  9. You now have a fully bootstrapped jig which may be clamped to a workpiece with holes positioned as desired, then the router with the custom base may be plunged at each intersection to create the required holes.

The accuracy of this procedure depends on the miter-slot-rail precisely fitting the slot cut by the dado bit in making the grid of dados. Any size rail and bit could be used as long as they match without slop.

The accuracy also depends on the squareness of the two edges which are referenced in beginning the initial dado (step 4) and perpendicular set of dados (step 7).

Any size hole spacing is possible, as determined by the initial distance from the miter-slot-rail to the bit in step 1.

Any size hole is possible, as determined by the final bit chosen in step 8.

Now that the puzzle isn't haunting me anymore, I'll probably use the pegboard solution anyway and save routing all those dados. I still haven't found the right rabbet/bushing/cutter combination to enlarge the original by exactly the amount required to use it as a template, but that's ok because this procedure will work just fine!

Thanks for all the mental stimulation to get me this far... and please tell me if you think there are glaring holes in either the pegboard or dado based procedures.

-Ashley
AshleyJ is offline  
post #30 of 45 (permalink) Old 09-16-2019, 06:16 PM
Registered User
 
Join Date: Aug 2014
Country: United States
First Name: Larry
Posts: 52
 
Default

Inor, If you learned to use the metric system you would never go back to 64ths. The Brits also gave up their Pound, Shilling, Tre pence long ago. They use the decimal system for everything. At least we do for money.
As for the project at hand, find a shop with a CNC router and have them make your parts. Way easier and very precise.
Larry42 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Router Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome