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Modellaner

Tensiometer

by Modellaner Feb 28, 2018
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Wow! I very seek this and i find it!!!! Very Thanks !!!

Thank's for gratulations :) I'm glad to read that :D hope you find it usefull ;)

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Holy shit, you did it. I had this on my "todo" list for a while, no reason why it shouldn't work, but you beat me to it. Thanks!

Definitely going to print this out as soon as I can and I can compare it to my FSA. Have you done anything for a fixture for calibration?

:D Yes I did it! I was wondering about that no one has made and uploaded this first.
I made this 1 1/2 years ago but I didn't find the time to upload this here ...
I don't have the money and requirement for the "original" one.
So I can't say how exactly it works. But I made a wheelset, centered it, tried the tool and the values are nearly correct. I have to confess though, that the dial gauge is a cheap one from china. Other than this thank you for your feedback, I really appreciate it :)

That is really awesome - I've done the research and had most of the ideas but not all the measurements and honestly didn't want to take apart my gauge. Really, really looking forward to printing and assembling this, I've already ordered the linear bearing. I think I'm going to go with a digital gauge for mine. The only problem I have is right now my printer that's big enough to print the body isn't working so all I have is a Monoprice with a 120mm print cube and the body is just ever so slightly too big, so I'm going to have to be patient and wait for the new printer to come.

I do have to ask - you list "1* spring" which is really, really sparse on information. Do you have any dimensions for the spring, or a part number, or anything like that? I know this design doesn't need a strong spring, but it'd be nice to have a better idea what to go with. Everything else I either have, or will have soon.

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Oh I must say that this is not the original one. So it's inspired by it but I got creative with the whole measurments ...
yet I think that it doesn't matter for the function. Only if you plan to use the digital dial gauge with the pc software you could have problems
because of the different distance between the two bearings. But that's all a question of calculating the tension.
About the spring: Unfortunately I can only write about the measurments not about the spring constant or force
(but of course you'll need the spring constant/force to calculate the spoketension).
The dimensions are: wire diameter: 0,9 mm, lengh: 20 mm, outside diameter: 9 mm and the inside diameter is about: 7 mm
(just to fit over the pivot from my dial gauge).

I think I ordered the spring from ebay (EU) but I don't remember the exact shop.
Here are two pictures of the spring:

Other than that, I'm looking forward to see your result :)

Update: I am able to print all the parts but the main body on my Mini - the carriage fits - JUST fits - the 120mm cubic build volume when turned 45 degrees and any skirt is turned off. I'm waiting for the linear bearing to arrive and already have the digital indicator. Still have to find a spring and confirm I've got the necessary hardware. Only challenge remaining is the main body, and I might have my big printer working just well enough to bang that out before I sell the whole printer. The spacer ring doesn't match up with the holes on my digital indicator, so I might have to modify that design, which means I might have to do the same with the main body.

By the way, I had no idea what an "Inbus" screw was, but I think that's just what we would call a "socket head cap screw" such as this one. Some folks might also call it an "allen screw" but I think that name comes from a brand, like Inbus.

Update to my update - took another look at the body and realized it's only slightly wider than 120mm. I clipped the edges in SketchUp and should be able to print it. Checked my dial gauge and it's 33mm centers for the square pattern on the back - close, but not quite the same as the 32mm square on your design, but that's an easy fix. Now to source the spring and we should be looking good!

I think the design is a little bigger than the original so unfortunately it doesnt fit into all printers.
I get the linear bearing as a "used" one from ebay (EU) (because it was cheap). I am interested so where did you get it from?
If you have problems with the holes of the dial gauge tell me about and I will se what I can do to fix it.
Yes youre right, the screw that I mean is a "socket head cap screw" (didnt know the name in english so I caled it "inbus" like some folks in germany it call.
I am verry excited to see your made one :D

I actually haven't compared the dimensions to the original, I could do that. Either way, just a little trim off the sides brought it under 120mm - I literally just chopped off where all the chamfers meet - see the attached photo. The dotted line to the right of the body is the 120mm distance, so I'll be able to print it completely!

As for the linear bearing - "used on ebay" is exactly what I got as well. When I saw your parts list, I did a google search and found the new ones at $80-85 USD and was like ... I dunno about that. Then, saw used on ebay for $33 USD and thought - this I can do!

Holes for the dial gauge - no biggie, I've already drawn up a new spacer (it's not the most complicated design) and will print that to see how it works. Modifying the body won't be terribly hard as well.

Nuts, I just took measurements off the body model and see it's sized for a 54mm diameter dial indicator. My digital one is about 57.25mm... so that body design won't work for me. Completely hadn't thought to verify the size of the dial indicator.

Uh okay. Which dial gauge are you use? Can you send me a picture in whitch you mark the relevant messurments?
Then I will see if i can change this.
Othervise I can send you the original files as .ipt from Inventor 2016 so you can change it to your needs.

I got this digital one from Amazon - the mounting pattern on the back is 33mm square, and the body is 54mm in diameter. Silly me thought all of these gauges used the same pattern. Unfortunately, finding info on the mounting pattern of cheaper gauges like these is probably going to prove near impossible before purchasing. Where did you get yours from? Since it's not expensive, I could just get the one you've got to make sure it works, and then take it from there. I'm also curious to take a closer look at my FSA to see the details of that one.

I'm away from home for the weekend so won't be able to get the photo until Monday at the earliest, but I can include one photo of my progress so far....

At first - your parts seem to be better as mine (with what material have you print it?) looks verry good, thumbs up!
Then - i think the glue sticks you use are the best for 3d print (have the same but from different seller in EU) this note had to be :D
So here the cheap dial gauge i have buy in china:

https://www.ebay.de/itm/Precision-Tool-0-01mm-Accuracy-Measurement-Instrument-Dial-Indicator-Gauge-/152640967565

Seems they ship to America, but I dont know how much it costs.

Nevertheless I think, we should to get the design ready for your digital dial gauge.
So I will change the diameter of the main body by my interpretation of your informations and then upload it here
Have you checkd the shaft from your dial gauge, if it will fits into the tensiometer boddy?

Material is AIO Robotics red PLA, I've been really happy with the quality, and I like that it comes in smaller 500g rolls so it stays fresher and I can have more colors.

Glue stick was necessary for the long carriage piece due to warping, but even at that, it pulled up and took the buildtak sheet up with it! Had to press the buildtak back down on the bed once I pulled the part off.

One thing I'm curious about is if there is a more common standard mount dimension for dial gauges, if there's a particular size that's used by more of the inexpensive dial gauges, then it'd make sense to use that.

Here a picture from the changes i made. Is that what you mean?

Yeah, that's it exactly! I checked the offset distance from the back face and it looked about the same as on your original design, so with just those changes that might be usable!

Oh, found the spring in my ebay list :D
Here it is:

https://www.ebay.com/itm/4x-Feder-Z-Achse-Druckbrett-Metallfeder-Druckfeder-3D-Drucker-/282358826710?nma=true&si=hORGSMNWXN2WI%252Fj%252FOvWkkc5h2kA%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557#shpCntId

They only sell and ship off in germany and on the other hand the offer was closed.
Hope this information can help. Ah, I remember that the spring can be a little longer (maybe 24 mm or 25 mm)
but that depends on your dial gauge. In my made one the spring is loose and falls arroud a little bit.

Oh, I was asking which dial gauge you had - not so worried about the spring, there's a much wider range of what'll work for that. I figure I'll head to the local hardware store and see what they've got in terms of springs, I imagine I'll find one that will work.

That looks like enough for me to get started, thanks!

Man, this thread is hard to follow as it sorts the replies all over the place! :D

Huh, this is funny - your ebay link for the dial gauge, same seller has what appears to be the same exact gauge I got on Amazon:

https://www.ebay.de/itm/Digitale-Dial-Indicator-0-01mm-0-0005-Bereich-0-25-4mm-1-Prazisions-Messuhr-/152372723706

So that might be a good one to model for as it must be a standard design that's widely available.

Modellaner
just now

Jep, agree with you the thread is a little heavy to follow (maybe we can clean up a little bit (but dont know how)).
So i made the changes to the main body and upload it as "Tensiometer - body (for digital dial gauge)". At this point - seems that the digital dial gauge from the ebay seller, from which I bought my "analog dial gauge", only sells "your one from amazon" as a version without the USB-conection feature!?
Nevertless agree with you, its defently good to know that we can order this digital dialgauge all over the world and especially for less money, that also will fit in the new design.
Hope the new design will fit ... . And wish you a nice weekend!

Oh, I missed that the ebay version is missing the USB. When I looked for a gauge I saw the digitals and thought it'd be easier to read, and when I saw the USB option, I didn't even think about confirming size, I just ordered it. With the USB option it looks like we can have an inexpensive alternative to Ric Hjertberg's awesome digital as that can enter readings directly to a computer as well.

I'll try printing the new version of the body today, thank you!

Okay, latest update I took your newest body model and loaded it up into MeshMixer and cut off everything but the mount for the dial gauge so I could quickly print just that as a test. Made a test print of that and everything lined up perfectly, the gauge fits in quite nicely. After fighting my printer for a little while, I just started a print of the full body for the digital gauge, so hopefully I'll have something by tonight.

Update - I've got the body printed, and it's good, but still some issues:

  • Minor - looking at the spacer ring, I realized it could just be integrated into the body, so I measured the back case cover for the gauge and raised that up in the model. I attached the modified STL for the body.
  • Major - I bought a gauge with a 25.4mm travel, but this looks to be designed for a 12.7mm travel. (see the first image - the end of the gauge interferes with the one piece being installed. Oops! I've ordered a 12.7mm gauge, which isn't a problem as I'll be able to use the 25.4 elsewhere.
  • The bolt holes are too tight across the design for the screws to fit through, I think my printer might slightly undersize the holes, but I have to thread the screws through the holes where they should just push through. I think oversizing the bolt holes by a little bit would address this, like going to 2.3mm for the M2 bolt holes.
  • The linear bearing mounted up nicely and works very smooth.
  • I'm wondering if the overall length of the 12.7mm digital might be longer than your dial gauge, in which case the carriage might need to be lengthened a little.

At this point I'm waiting for the 12.7mm travel gauge and the bearings, and still have to find a spring, but it's looking really, really promising.

I just realized looking at my photo that if I were brave, I could use a cutoff wheel on the extra bit of my 25.4mm travel gauge, and I'd even have a smooth face for contacting the spoke, but oddly enough I think I'll wait for the proper one to come in.

Oh no, sorry that with the dial gauge travel was my fault ...
So if the new one would not fit I can change the carriage to your needs.
I have just update the thing description by your informations. Thanks for that!
Did you ordered a new digital or analog dial gauge?
Your printed one looks very nice! especialy the color arrangement.
I remeber that I drilled the 2 mm holes a bit to fit with the screw. But I will fix that in the file.

I look forward on your progress with special interest.

Not your fault at all. I saw "1* dial gauge" and read it as "1" dial gauge" so got the 1" version - 25.4mm Didn't realize that it was an asterisk and not a double quote and was so excited to see someone did a tensionmeter that I didn't bother to check the dial on my FSA.

Looks like this spring is promising: http://a.co/boyvdcz

10mm outer diameter, 0.8mm wire diameter means a 8.4mm ID will fit perfectly over the 8mm top cap of the gauge. 25mm might be a bit long but we'll see how that works out. Other than being 5mm longer than the one in your photos, it should work quite well.

Another thing that I noticed looking at my FSA tensiometer - it does not use a linear bearing like this design, there's nowhere near enough room. I don't want to take it apart to prove this, but I'll get some photos. Would be interesting to try the design without the need for the linear bearing, don't know if it could be made so that it slides smoothly enough without -- but that's a discussion for after I get a working version of your model as it is.

Ah yes the spring will work for sure (25mm is simply perfect) because my one was a little short and falls arroud as descripted.
I am very interested at the construction of the original FSA one. Unfortunately you dont want to dismantle but I understand the reasons for that. Since I designed this I was thinking about the possibility to realize it as easy and cheap as possibil. But I cant find any informations about the construction of the original one. And I decided to take a linear bearing for that but also think that a "non linear bearing model" is more practicable to make/build. Otherwise how easy and cheap can it be constructed and still be precise like this model.
The idea to integrate the spacer in the body is well, I update it to the hosted Model.

I think we'll be able to figure out how to duplicate the FSA design without the separate linear bearing, but there will be challenges, tolerances of different printers and keeping friction between printed parts low - so the current design using the linear bearing is an excellent place to start, as it's going to be more predictable .

Regarding the linear bearing, I'm learning a little about those, and it looks like that's just a standard 9mm linear rail guide, and it looks like this model on Amazon would also work, although it's 100mm vs. 80mm. This gives a less expensive option to having to find the TSK LMBM9 used.

I think if I get a bunch of measurements and photos of the FSA one, we should be able to get a good idea of how it works without having to disassemble it. My biggest concern with disassembling it isn't being able to get it back together but more towards a concern if the accuracy would change at all. That leads to my next thought - once I have a working version of your current design, I'll want some way to create the tension chart for it, and that'll involve building a testing fixture. I've already done some work towards that end, so I think getting that working should be the next step. I've ordered this digital scale and will get to work building a fixture to mount up a spoke so I can take readings.

In the meantime, I'm just waiting for the 12.7 gauge, springs, and bearings. Should be able to have a workable gauge by the weekend, I think!

I agree with you, the tollerances between ours all printers are probably to much to change the design now.
But it seems you have an idea how the original FSA work!?
Unfortunality I cant open the link to the linear bearing on amazon can you check this?! Seems to be a good alternativ possibility to change the expensive one. I undestand your reasons its like as I wont disassamble my one (if I would have the original FSA) its not guaranteed that it works like before when you assemble it again. I am greatful if you can make the tension chart for it because I still dont have the money for hardware (like a "load cell" and other stuff) and time to do that.
Hope we see your made one by the weekend, I am so excited.
( I apreciate you will upload it as a "made one" !? hope so because it will be a nice easter egg for me/us :) ).
Until then I wish a pleasant week!

Oh I definitely wouldn't change your current design - I think it's the best approach for working with 3D printed parts on a variety of printers. I think duplicating the FSA design will be a fun challenge once this one is all sorted and we've got a working test fixture. (see the attached pic for my work on that tonight)

Thingiverse does weird things to Amazon links. Here's a link to the linear bearing as code so hopefully they don't mess that up: https://www.amazon.com/dp/B018KFFRAE/ If that doesn't work, I attached a screen shot of the page as well. Hard to tell from the photos and the listed specs don't say, but that looks to be the same 10x15mm bolt pattern on the slide carriage.

Once I have mine all assembled, yes, I'll definitely be uploading it as a make, I try to always post makes!

I'm also really excited for the progress, really want to try this out on a wheel!

Here's some detail photos of the FSA with some comparisons to the printed one. It looks like there's a flat piece of aluminum which connects the palm handle to the curved piece that side loads the spoke. Doesn't look to be any type of linear bearing, there's just a guide with wings that fit into a slot at the spoke side, with the force of the spring acting along the same axis as the spoke contact point, I think there won't be too much friction in that design. I'm also thinking that I should be able to pull off the palm handle to see how that all fits together without having any trouble putting it back together.

We will see I am interested to change the linearfixture but yes firstofall we (you) should do the calibration.
So your ideas for a test bench/calibration tool looks great! The link even dosent work (as a link in the thing description) but I have upload the photo. I have copy the link intro another tab of my browser to look at that. Maybe it fits but I cant read the messurments from the pictures.

My challenge on the test fixture is how to mount the lower end - it should be solid but something that can be quickly opened up to kill the tension, as the crane scale will need to be reading zero when it turns on, then tension applied before it auto powers off. Have to figure that out.

Maybe you can use something like this to solve the issue:

That's funny, that's exactly what I was thinking of setting up. Don't know if I can make one or if I can buy one that would work. Did a little searching and http://a.co/daoqmfB looks promising. This also looks promising: http://a.co/i8kaMA1

Curious if I could print something that could survive the ~100kgf force of a fully tensioned spoke, but that might have to be a future project, especially after I have a printer that can print something in higher strength plastics preditably.

This guy has essentially the same approach (using steel for the frame, I'm planning on using wood) with a crane scale, and he doesn't have a quick release - I think it'll be the easiest to start with that part hard mounted to start, and see if I have to set up a toggle.

The one from the video looks best for this. So if you ask me I would prefer the steelbuild one because its more stable as a wooden one but maybe hard to build (depends on the tools).
I have a look at your pictures and also on the webside but I cant imagine how it works with the rail system. Okay, the guide with wings on the spoke side, that's logic, make sence and will work. But I dont imagine what's on the otherside between the body and carriage.

Update:

I found this picture in the thread from the link you have post.
It looks like there is nothing else then the guide on the spoke side, to hold the slide carriage in position.
Would you say that the spoke and handle do this on the handle side !?

There is a cylinder at the top of the gauge that I think contains the spring, and I think that's what acts as the other guide. If you think about it, the force at the spoke is exactly in line with the spring so there shouldn't be much in terms of side forces to bind it up even with such a simple bearing setup. Now mind you, machined carbon fiber will likely slide more smoothly than 3D printed parts, but I think that could be addressed as the printed parts can still be sanded. I think it's doable, and it's gonna require a bunch of prototypes, which I'm looking forward to! (I think if we go down that road we're going to need to find another forum than a single massive reply thread here!)

Got some more progress tonight, with the 12.7 gauge it fits, but my gauge rod is longer than yours so it doesn't open up at one end. I modified the handle to shift the mounting holes 5mm, and it works! I'll post photos in the morning.

Only problem now is all I need is the springs, and the damned order looks like it won't be in for about two weeks! Gah!

Ahh, that makes sence, ofcourse :D Now I can imagine how it works. Thanks! Yes, we should do this and we defently have to look for another forum. You have any Idea where we can get with this? Maybe we should start a topic in a group on thingiverse!?
Or do you have other proposals/ options?

I guess moving the discussion to one of the bike related groups here makes the most sense. I really like the new Discourse forums for Octoprint but I guess it's not the best place.

There are three bike-related groups here that I know of:

The first one "Bike" has the most members, so I'm guessing that makes the most sense.

Here are the photos from last night's reprint of the handle. I had to move the mounting holes 5mm to get clearance for the spoke to go in when the tensiometer is held open, and I just modified the STL to accomplish this. I also made the countersink holes deeper as my longest M3 screws were slightly too short to reach the nuts. All I need now is the springs, which looks to be delayed, so I might have to hit a local hardware store and see if I can find something that will work.

Photos posted out of order. Here we go:

In other news, I got the scale for the tensiometer calibration fixture, and I think it'll work really well. I think a metal frame would be good as well, but outside my fabrication capabilities. With thick enough wood (planning on at least one 4x4" for the "backbone") I don't think it'll be a problem.

Damn, think there no standarts for dialgauge dimensions :D
But well done, your model looks great (especialy the printed parts are much better than mine and with the digital dial gauge... , very nice)!
Now you have just to find a spring for it or we have to wait until your order will arrive.
Finally I start a topic for "Tensiometer" in the "Bike" group.
I think thats the best place, because there the most members and things for bicycles).

I guess there's not much incentive to have standards for these - they're usually used with whatever mounts the manufacturer comes up with, and most folks aren't putting them into 3d printed parts.

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