I disagree here and the reason is that it is very hard to measure hole to hole with a tape. There is inconsistency in how and where you might “hook” the tape, tape sag between holes and what angle you look at the tape.
I have one, which I think I forgot to update this thread about my experiences. I like the idea for measuring sub-millimeter at the end of the tape, but the other issues I mentioned above are still a problem.
If we laser etch a submillimeter scale at the ends, where it is needed, I think we can have something that is easy to do by yourself, rigid, thereby (practically, compared to tape) eliminating flex in the measuring device, and a consistent “anchor” method to the drill holes.
I disagree here and the reason is that it is very hard to measure hole to hole with a tape. There is inconsistency in how and where you might “hook” the tape, tape sag between holes and what angle you look at the tape.
I have one, which I think I forgot to update this thread about my experiences. I like the idea for measuring sub-millimeter at the end of the tape, but the other issues I mentioned above are still a problem.
what were your experiences?
If we laser etch a submillimeter scale at the ends, where it is needed
unless you intend to do a vernier type scale at one end, you need the sub-mm
scale across quite a bit of length to cover the different size machines.
without a vernier scale, how accurate are you going to be able to make the
marks?
Well, I wish I would have asked my co-oworker to make two; it would have made anchoring the tip of the tape easier and more accurate. The resin print turned out beautiful but there needs to be a more robust way to clamp the scale to the tape. I see benefit to gaining measurement resolution but not necessarily accuracy due to the inherent issues with a tape measure, which I listed above.
Well, I wish I would have asked my co-oworker to make two; it would have made
anchoring the tip of the tape easier and more accurate. The resin print turned
out beautiful but there needs to be a more robust way to clamp the scale to
the tape.
yes, they are intended to be used in pairs.
first off, the one on the end has a round pin to put in the hole, second it’s
vernier lets you figure out how far off the end of the tape is.
the ones I’ve 3d printed have a fairly stiff fit between the holder and the main
part, but a rubber band across it would help. I thought about including a screw
hold to provide a clamp, but thought it would cause more grief than it solved.
I see benefit to gaining measurement resolution but not necessarily accuracy
due to the inherent issues with a tape measure, which I listed above.
That is a valid point. I think using a pair does improve accuracy, if only in
that you are better measuring hole-to-hole than trying to figure the center of
the hole against the tape.
I don’t think so. Just as your 3D print scale is at each end, so should the laser etching. If the steel is laser cut on a professional machine, I think we will have an accurate measuring stick.
I said stainless because, well, who doesn’t like stainless but, no reason it couldn’t be made out of cheap carbon steel. Just keep it oiled (reminds me of my younger years cleaning out the shotgun after hunting)…or not…a little rust never hurt anybody
@dlang. I still like the idea of concentric, telescoping steel tubes with vernier scales but it isn’t financially practical (pushing >$60 just for 1/2" cut steel, not including “nubs” to press into the holes, and before laser etching scales). I think I’ve got it out of my system now
Thinking cheaper…Use a wood dowel. A 1/4" (or slightly smaller depending on actual bit diameter) bolt fastened to one end of the dowel will act as the “nub” that is pressed into the first drill hole. To measure the distance between holes, a 3D printed sleeve, with a nub for the drill hole, can slide up and down the dowel to measure the hole spacing. The sleeve would need to have ~3/16" of material removed down the length of the sleeve so it can be clamped with a Trigger Clamp. This would allow the dowel to be removed and placed on a table where a tape measure and 3D printed vernier scales can be used to reliably measure the full length (bolt OD to sleeve edge). Calipers can be used to deduce the actual dimension from the edge of the 3D printed sleeve to the center of its nub (which is the center of the drill hole).
But alas, I don’t have a 3D printer
EDIT:
Another thought is to have three separate dowels; one for the short distance measurements, medium distance measurements and long measurements. Standard closet rod dowels are 48"/1219.2 mm (also 96") and can be used for all three.
The “long dimensions” for Holey are between 1198 and 1197.5 mm. Fasten bolts at both ends, without the sliding sleeve, so the distance is exactly 1198 mm, center to center. Insert one bolt into the drill hole and measure the error from the second drill hole to the second bolt with a pair of calipers.
A second dowel for the “medium dimensions”, which are between 963.5 mm and 959.5 mm with bolts installed so that their center to center dimension is 960 mm. Insert one bolt into the drill hole and measure the error from the second drill hole to the second bolt with a pair of calipers.
A third dowel for the “short dimensions”, which are between 711 mm and 710 mm would be needed and bolts installed so that their center to center dimension is somewhere in between these 710 mm. Insert one bolt into the drill hole and measure the error from the second drill hole to the second bolt with a pair of calipers.
I suppose the same could be done with cheap carbon steel tubes to avoid distortion in the wood due to changing heat and humidity. One difficulty with this concept is fastening the bolts straight through the dowel with precision. A drill press would be required. Maybe a machine shop would make these for super cheap and shipping shouldn’t be too bad in the US. Another difficulty would be holding the dowel and calipers steady. Like the other methods, additional hands would help.
