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3D Printed Tool for Hub Shimming/Setup

Awesomeness

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I have one of the hub covers that has been machined down, for use in setting up the hub shims. I figured I'd design a 3D printed variant, so that people weren't always having to buy/make/mail the metal kind.

I haven't printed one yet, but here's what I have so far. I'm going to do some work on my hubs in the coming months, and test it out.

FMTVHubSetupTool-3DPrinted.jpg

EDIT: Ah, drats! It looks like it's just a little two big for the bed of my printer. It's a little over Ø8.5", but the bed of my printer can only do 9.84"x8.30" (max). Maybe I can trim some off two sides, and lose the use of a couple bolts, and still get away with it. It will be in the neighborhood of a 32 hour print, but not too expensive on filament.
 
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Floridianson

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Looks like a good plan. Don't know if you plan to design it with all the mounting holes but if it is strong enough then it would seem like we would only need the eight to hold in the cross and gears. Believe when setting up the hub we could remove the cross O rings for the set up and replace them when ready for final install of the real hub. Just another thought. Could you just do half of that mold. Would be nice to be one piece but installing two pieces to hold in all four point of the cross would still work.
 

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ramdough

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I just read your PM you sent me yesterday....... that made my last response not make any sense.

I appreciate all of the effort you are going through to help out the hobby.



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Awesomeness

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Looks like a good plan. Don't know if you plan to design it with all the mounting holes but if it is strong enough then it would seem like we would only need the eight to hold in the cross and gears. Believe when setting up the hub we could remove the cross O rings for the set up and replace them when ready for final install of the real hub. Just another thought. Could you just do half of that mold. Would be nice to be one piece but installing two pieces to hold in all four point of the cross would still work.
I think we're thinking the same thing. Are you saying that since we probably only need to use the holes marked in red, I'm free to cut away at the unmarked holes to get it to fit on the printer?

I only need to knock 0.2" minimum off, or something like 0.5-0.75" would be better. That looks about like this below. So if I remove those holes at each 45° (which would get cut), and rebuild the outer wall for strength, it should be ok. That's what my plan currently is.
FMTVHubSetupTool-3DPrinted-FitToBed.jpg

I'm interpreting your other suggestion as cutting it into two pieces, in order to only have the minimum necessary to hold the cross in place. That would look something like this below roughly, and you would need QTY 2. I hadn't really considered that (mostly because the above would work on my printer), but it's certainly not hard to do, for those that have much smaller printers.
FMTVHubSetupTool-3DPrinted-SectionView.jpg

I was asked...
What tolerances do we really need on the radius and surface of the semi-circular cutouts?
- I'm not sure what tolerances we really need on the semi-circular cutouts. The way I designed this, I drew one circle that is exactly the size I measured from the real metal cover that I have, then I drew a circle 0.005" bigger and used that larger circle to make the cutout in my model. The reason for that is I now have introduced a 0.005" tolerance (so my printer could print the cutout 0.005" too small and it would be exactly the size of my metal cover). Every printer is going to be a little different, but it gives me the ability to go in the model and adjust that 0.005" to tweak the results we're getting, without messing with the inner circle diameter which is the real target.

What about the tolerances on the height from the base to the semi-circular cutouts?
- I'm not sure what the tolerance on the height of those cutouts is either. When I measured the cutouts with good calipers, and averaged between the 4 cutouts, the number I came up with was within 0.001" of 32mm. So I'm assuming the true diameter of that cross pin is 32mm. Then, when I measured the depth of the cutouts, and averaged, I was again within 0.001" of it being 15mm deep. On one hand, that number makes sense, 15mm is half of 30mm. On the other hand, I expected it to be slightly less than 15mm to account for the thickness of a gasket. But I guess it works just fine at 15mm deep, so we'll roll with it for now. If we're having problems holding the cross pins down, it's an easy thing to adjust.
 
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Floridianson

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No gaskets just the cross O rings. If we were to remove the O rings we might be able to get away with just a top cap and bottom cap to hold the cross in if the plastic is hard enough. As per Steve's advice we place the cross with one set of gears horizontal and the other vertical then we are just feeling the play at the bottom gear or the gear at the six o'clock position. This way it would end up being just two small pieces just to hold the top and bottom of the cross. Not good on drawing but if the two caps were strong enough then we would not need what I have in red. One piece would be nice as I said but it would not be a problem or extra time to installing two. One at top and one at bottom just have to remove the four O rings. With the O rings removed the cross fits pretty tight in the housing with just a small push of your hand to end up metal on metal. What ever you think is best for you and your printer. I just cut off the face of an old stock cap to do mine so I could reach in and do the feel it thing. Looks like your shaved one would be just fine too.
 

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Awesomeness

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No gaskets just the cross O rings. If we were to remove the O rings we might be able to get away with just a top cap and bottom cap to hold the cross in if the plastic is hard enough. As per Steve's advice we place the cross with one set of gears horizontal and the other vertical then we are just feeling the play at the bottom gear or the gear at the six o'clock position. This way it would end up being just two small pieces just to hold the top and bottom of the cross. Not good on drawing but if the two caps were strong enough then we would not need what I have in red. One piece would be nice as I said but it would not be a problem or extra time to installing two. One at top and one at bottom just have to remove the four O rings. With the O rings removed the cross fits pretty tight in the housing with just a small push of your hand to end up metal on metal. What ever you think is best for you and your printer. I just cut off the face of an old stock cap to do mine so I could reach in and do the feel it thing. Looks like your shaved one would be just fine too.
Not having done this myself before...

1.) Why would you want to not have the o-rings on?

2.) Why would you only need 2, and not 4, caps?

I have one of the stock metal caps with the face milled off. That's what I measured to make this.

Here is a truncated one, to fit my printer (8" across flats). Making 2 (or 4) little caps would be easy, and print faster. How much more helpful do you think it is to have it as one piece?

FMTVHubSetupTool-3DPrinted-FitToBed2.jpg
 

Floridianson

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Yes four point clamping would seem to be the best in this case. The O rings seem to be the only thing that really holds the cross from the metal to metal contact when it is seated into the hub. When we use the cut off metal cap it for sure crushes them down and we get the metal to metal that we need to measure the gear play of 10/20 thousands. I don't think if you took off the O rings and put the cross in with gears on and held it in with your hand you could not even measure the space between the cross seat and hub. Just make it like you have it slimed down in your last pic so it will fit the printer and one piece four point bolt down and it should be good to go.
 

ramdough

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How accurately can you print these things?

I think the last concept would be the best. At least the entire ring is aligned to itself and not introducing any new variables. (Besides this not being a machined cap).


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Awesomeness

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How accurately can you print these things?
I think the last concept would be the best. At least the entire ring is aligned to itself and not introducing any new variables. (Besides this not being a machined cap).
Pretty accurately. I have a part here on my desk (the inclinometer mount, from my other post) that is modeled at 6.900" wide, and the printed part measures 6.887" (0.013" undersized, across a nearly 7" span). Another face across it that is at an awkward angle (more challenging to print accurately) is modeled at 2.120" and measures 2.127" on the printed part. My printer (Prusa i3 MK3) is one of the best prosumer/hobbyist/small-business FDM printers out there, but even a lower quality one should get in this ballpark (maybe 0.025"max). Smaller distances, like the cutout for the pins, should hold even closer.
 

Floridianson

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I did all six of my hubs over a year ago and what I did just for smitts and giggles was rotated one hub around and checked every gear at the six o'clock position. Seemed to be the close to specs on every gear so I did it just on that one. With a cut metal hub or your printed one at least the four points of the cross are pulled down tight into the hub. Post a pic when you get one done .
 
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ramdough

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Is there any concern that the printed one will flex and not hold everything tight?


I have a steel one, so this would not be an issue for me. Just curious.


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Awesomeness

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Is there any concern that the printed one will flex and not hold everything tight?
I have a steel one, so this would not be an issue for me. Just curious.
I don't know. I'll start fairly minimized, like in the picture. If it flexes, I'll add reinforcement ribs, and try again. If that doesn't work, I'll fill the area over the pins in solid, and it will be quite strong.
 

Awesomeness

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I printed a thin section of the whole shape, and held it up to the real metal cover to verify bolt hole accuracy. Looks pretty good.

I also printed a single pin-cap section about 3" wide, with a reinforcement "X" over the pin cutout, at 80% infill density. The thing is stupid strong... you could probably drive the truck over it. So it wouldn't need to be printed nearly that dense, I don't think.
 

Awesomeness

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I printed one, but haven't used it. My hubs were running ok, so I haven't tried changing the shims. If you want to pay to ship it, I'll send you the one I have, for you to try out.
 

coachgeo

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here is the no old hub / Calliper measuring tool method.... pretty simple math. would be interesting to do both ways and see if get same results.

video link starts you off at how to measure/calculate for shims
 

Awesomeness

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With either hub tool (machined old hub or 3D printed), it's just letting you take the measurements with it actually assembled in the hub. The "old way" is that you measure the parts outside the hub, and calculate what size they will be when assembled. So if you do it well, there is no difference, but with a hub tool you're just taking actual measurements so there is less stuff to screw up calculating.
 

coachgeo

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With either hub tool (machined old hub or 3D printed), it's just letting you take the measurements with it actually assembled in the hub....
need a video of someone using the cut hub. Its been explained in words but found it confusing.

also with cut hub.. don't you practically have to install everything.. measure..... then uninstall everything to put shims in?
 

Floridianson

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need a video of someone using the cut hub. Its been explained in words but found it confusing.

also with cut hub.. don't you practically have to install everything.. measure..... then uninstall everything to put shims in?
Yes with the cut hub if your off as too tight or too loose you have to pull it back apart and correct with shims or remove shims. I still like the cut off hub way even if I have to go back in. I had to do all six of mine and after the second one I got faster and did not mind going back in.
 

Third From Texas

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I printed one, but haven't used it. My hubs were running ok, so I haven't tried changing the shims. If you want to pay to ship it, I'll send you the one I have, for you to try out.
There is a fellow over on FB LMTV about to drop in his 3.07's who was asking about methods and measurements techniques. If he is going this route, he would be a good candidate to tinker with it. Let me ask if he's a member here.
 
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