Metal Top Pantograph kit available

Yes, that looks right (and looks like the measurements I’ve been telling people have been wrong, oops)

It may be too many years of watching “this old house” and “new yankee workshop”, but I really try hard to use the story-stick approach of ‘put the small hole at the bit and drill through the part’ rather than measuring. That makes it so that people don’t end up translating from imperial to metric and if the parts are the wrong size (as long as they are consistent), everything will still work.

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I ordered a kit from David Lang earlier this year and just now getting it put together. I will update progress with the pantograph installation here.

@dlang, correct me if I’m wrong but I believe this is the way you described assembling the linkage? Of course, this is just a loose, temporary assembly.





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almost, the center bar should be between the two horizontal bars. the way you have it they horizontal bars will pinch a bit (the center ends are closer together than the outer ends)

Okay, like this:

exactly. Now you just use one of the side arms to drill the holes exactly
corresponding to how your router mounts to the sled, and tighten the nuts so
things don’t have play, but move freely (which is why the kit uses nylock nuts,
the next ones will include only nylon washers)

David Lang

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More progress pictures (note uploading pictures from a phone doesn’t work well…can’t see the image after uploading).

This how the bit looked poking through the sled. Note the router is mounted to the sled and the sled is flipped upside down. I put the small hole at the bottom end of the arm on the tip.

I clamped one of the vertical arms (looks like a hook) to the sled and positioned it so that the little hole in the hook end is centered on the router bit.

I then drilled through the sled. I’m planning to run bolts through the sled to mount the linkage.
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Since the linkage needs mounted a few inches off the sled, I’m going to try a 2x4. I clamped the wood to the sled and drilled some pilot holes in the 2x4 to mark the linkage mounting location. NOTE: this 2x4 will be cut to 2.5" once the holes are drilled on the drill press.

I hand drilled the holes through the sled but I am going look into redoing this on a drill press so that the drill goes through the sled and 2x4 at the same time.
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12/27/2018 Update:
Once I got the drill press, I looked into drilling new holes through the sled and 2x4 but it was too complicated to get everything all clamped together and drilled so I just continued drilling the pilot holes I made before.

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I drilled out the bottom of the sled to counter sink the hex head bolts.
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I did not have problems with the bolt heads spinning.

I cut the 2x4 block a bit smaller, per @dlang, and mounted the linkage. I put some washers on top of the 2x4 and lock washers on top of the linkage center arm.

I then used a hole saw to cut out the center.

I still need to add bricks, tighten up the linkage bolts and cut and mount the 1/8” sheet of HDPE to the bottom of the sled but.

Feb 11, 2019 Update:
I’ve been trying to improve accuracy (that is for another post) and decided it was time to catch up on documenting my installation. Completing the sled construction…

I eyeballed the brick placement which, in hindsight, isn’t a good idea.

As you can see, the weight is not balanced and causes the sled to rotate to one side. If the balance is really out of whack, I think this can cause issues with the linkage in the corners. I believe the center bar should always remain vertical (or at least more vertical than this).

After moving the left brick so that it is mirrored to the right brick, the center bar looked pretty well vertical in the extreme upper left corner:

If installed accurately, the bit should stay in place while the sled is rotated. @Jay_Settle pointed out to me that I should perform a “rotation test” to verify the accuracy of the installation of the linkage. With the sled connected to the chains, and centered on the work piece, I plunged a 1/4" bit down about 1/2" into a piece of plywood (via GC z-axis controls). Holding on to the router handles, I slowly and gently rotated the sled clockwise to about 45 degrees and then back to center; the bit stayed in place. From center, I moved the sled counterclockwise about 45 degrees and the bit moved down and to the right as you can see in this picture. Since I’m using my hands, it isn’t a scientific test (I could have unknowingly pulled more vertically or horizontally at any time during the rotation). However, I do think it is an indicator of the accuracy of the installation. I’m not sure I can do any better.

I would do this after actually mounting the router to the sled, so that you are really sure where the bit will be (and if the sled ends up slightly out of position, the linkage will still be centered on the bit)

I think that’s one of the advantages of @dlang’s design. I think many people’s calibration issues are related to the router bit not being perfectly at the center of rotation of the triangulation kit.

@dlang I did actually. I shouldn’t have posted the first couple of pictures without the router since that is confusing. In the picture that shows the bit poking through the sled the router is mounted to the sled and the sled is upside down. To drill mounting holes in the sled, it won’t matter if the arm is clamped to the bottom of the sled, I just found it easier to do on the bottom.

@dlang I’m updating my post above.

@madgrizzle Did you install the pantograph linkage? If so please share your install notes and results.

I haven’t installed it yet. I have cut the sled and mounted the router, but I haven’t had much of an opportunity to spend more time in the shed.

@madgrizzle
With this kit, the most critical dimension (center arm distance from bit) is in jeopardy of being altered because the distance is measured by putting a side arm on the sled but you can’t mount the linkage directly to the sled, so the mounting location has to “transfered” to a piece of wood that is a few inches above the sled. Since I don’t have a machine shop, this is difficult to do accurately. Since you haven’t tried it yet I understand your perspective. Instructions and help from those that have done it would be helpful.

Are you trying to drill all the way through the block? I see the difficulty you are talking about if you don’t have a drill press. I couldn’t manage to do it when testing out different frame designs unless I used my drill press. You don’t have to go all the way through the wood for this design, but the holes on each side need to be a the same spot. Perhaps using a jig or marks that ensures the wood is perfectly centered along the long axis would allow you to use the holes drilled into the plywood as a guide? Drill one side of the 2x4, flip it, and drill the other side. I’m sure @dlang has some suggestions.

Yes I planned to go through the wood to ensure the holes don’t move. Flipping the 2x4 was my 2nd option that I discussed with David previously but I think it is an invitation for innacuracy even building a jig. Unfortunately I don’t have drill press. I thought my friend had one but I was mistaken. A coworker has one but it would be a few weeks before I could get the block back (ain’t nobody got time for that!). I’ve always wanted one so I’ll probably just end up buying it.

Sweet Brown never spoke truer words. I’ve never used them, but there are relatively inexpensive devices that will “convert” a hand drill into a drill press. But nothing is better than justifying a large purchase based upon a specific need. I bought mine 15 years ago because I needed to drill one hole in one piece of metal… once :slight_smile:

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trying to build a jig that puts the holes exactly in the center of the block
when you flip it is hard. I think that it’s probably easier to try and drill all
the way though

note that you don’t want a 1/4" hole, you want about a 5/32 hole so that the
threads get a good grip into the wood

to drill the hole, my preference would be (in order)

  1. a drill press ($65 from harbor freight, watch for a 20% or 25% discount
    coupon) like
    https://www.harborfreight.com/8-in-5-speed-bench-drill-press-62520.html

  2. a drill guide ($33 from home depot) like
    https://www.homedepot.com/p/General-Tools-Drill-Guide-and-Chuck-36-37/100349264

  3. one person run the drill, a second person watch that the bit is vertical
    (possibly using a couple of right-angle squares as reference)

a completely different approach is to use the maslow to cut multiple layers out
of plywood, add a couple of holes for dowels to make sure they are lined up
(make them a tight fit so you have to pound the dowels in). This may take some
tinkering to get the hole spacing exactly right, and instead of doing the layers
side by side, do one, then move the workpiece and do the next. (The maslow is
very good at doing the same thing again and again, even if the dimensions you
put in the g-code don’t match the dimensions that are cut)

David Lang

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one the block can’t be that long (although you may want it that long to drill it). I designed this to have a block that goes 1/2" above and below the mounting holes (2.5" total), and even with that you will need to notch it slightly at the top to clear the washer for the top mount and one corner at the bottom to let the horizontal arm that is below the center arm to clear when it gets up to 80 degrees from horizontal for the bottom corners.

note that both of the linkage kits have the ability to reference on the bit and
drill through them to make the holes for mounting on the sled. (you aren’t as
likely to damage the metal compared to the wood, but they both have this option)

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I think the ring kit is the only triangulation solution (of the three widely in use) that suffers from that concentricity problem… Both linkage kits use one of the bars to mark/drill the sled. I’m actually not sure how the ring is aligned but it always seemed a little sketch to me.

I would echo @dlang’s hole drilling suggestions above and add one more to the bottom of the list. When trying to drill a hole perpendicular to some material alone and without a drill press I have had great success using a small mirror or even better a CD, place the reflective side up with the hole in the CD where you want to drill, now you can see the reflection of your drill bit in the CD. (you drill through the hole in the CD) Sight down the bit and make the bit and the reflection line up. If they make a straight line then your hole is perpendicular to the CD/surface. I’ve done this a handful of times in a pinch.

In my opinion the bottom line is: a drill press is worth having. I bought mine for $50, it had been laying in the snow and rain on it’s side for 8 years. But it was built in the 50’s so it’s solid and amazing! After restoration I use it almost every single day - no joke.

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This is great. All the time I’ve spent in Home Depot and I’ve never seen one of these before. Earlier this afternoon I splurged on a ~$300 drill press from Home Depot. Will have it in a week or less.