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Old March 8th, 2018, 11:44 AM   #1
ipixu78
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Default Inline Axles and tolerance to bearing.

Main question: Are current axle designs poorly manufactured/matched to frames or is there a reason for how they are?

I'm looking for answers from imaginative folk and those who make their own equipment and/or have taken measurement tools to their gear to dig deeper.

I think I 'want' a custom set of axles in my trick inlines, as I believe the tolerance of the axle and bearing/spacer interface is poor. I only tighten my axles 'finger tight.' I can torque the wheel and feel a slight wobble. This wobble creates clicking sounds as I do tight 3-turns and especially whilst doing toe wheeling tricks. I am afraid to tighten my axles further so I don't strip my frame threads. I imagine tightening the axles would have the effect of pinching the bearing spacer setup so that the frame is solidly mounted and less likely to allow the wheel wobble I am noticing.

I have taken my Mitutoyo Vernier Caliper to my axles to check their diameters.
- Steel Sebas (Igor Pro Frames) 7.90mm +/-0.01mm
- Aluminium Powerslide Axles (Alpha Frames) 7.78mm +/-0.01mm
(It seems that the SEBA Axles are made to a size closer to the 8.00mm 608 bearing. This shows there is at least 0.10mm of play between the axle and the inner bearing race ring.

Out of curiosity, I also measured the 7mm axles of my Roll-line Dance plates and found that the 627 bearings are an incredibly close match within 0.01mm!, for this reason my rink says there is less need to go to the trouble finding spacers that fit the wheel-hub design)

QUESTION: What is the reason they donít provide a better fitting axle on inlines?

I also noticed that at the threaded end of the axle there is an extended small area unsupported, that really should be to the axle diameter tollerance (i.e. close to 8mm).

Powerslide axle (on Alpha frame) approx. 2.39mm
Seba axle (on IGOR Pro Frame) approx. 4.40mm (over half the width of the 608 bearing!)

Iíd appreciate comments and anyone who has noticed this. There is a heap of info on bearing spacers, but I feel no one has really covered the question of speed-axle design and functioning.

Thanks for reading.
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Old March 8th, 2018, 12:31 PM   #2
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The most usual reason for small diameter is to allow a larger manufacturing tolerance range. Without going into all of the specifics, holding tight tolerances mean higher cost, larger tolerances are lower cost.

In the 'speed' section there have been a couple extended discussions about axles. (a couple years ago or more)

I have a bit of an idea as to why the end of your axles are relieved... It could be to allow clean tool runout during the thread cutting operation. Again... a long relief means easier machining which means lower cost. But, without photos it is tough to guess well.
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Old March 17th, 2018, 11:07 PM   #3
Mort
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Quote:
Originally Posted by ipixu78 View Post
Main question: Are current axle designs poorly manufactured/matched to frames or is there a reason for how they are?

I'm looking for answers from imaginative folk and those who make their own equipment and/or have taken measurement tools to their gear to dig deeper.

I think I 'want' a custom set of axles in my trick inlines, as I believe the tolerance of the axle and bearing/spacer interface is poor. I only tighten my axles 'finger tight.' I can torque the wheel and feel a slight wobble. This wobble creates clicking sounds as I do tight 3-turns and especially whilst doing toe wheeling tricks. I am afraid to tighten my axles further so I don't strip my frame threads. I imagine tightening the axles would have the effect of pinching the bearing spacer setup so that the frame is solidly mounted and less likely to allow the wheel wobble I am noticing.

Typically axles of "8mm" are made from 5/16ths stock. So if you check the OD on an axle it is unlikely to measure above 7.94mm however it really is a non issue. You NEED to torque your assembly down. This is what CREATES the stability and firmness of an inline skate.

I have taken my Mitutoyo Vernier Caliper to my axles to check their diameters.
- Steel Sebas (Igor Pro Frames) 7.90mm +/-0.01mm
- Aluminium Powerslide Axles (Alpha Frames) 7.78mm +/-0.01mm
(It seems that the SEBA Axles are made to a size closer to the 8.00mm 608 bearing. This shows there is at least 0.10mm of play between the axle and the inner bearing race ring.

Out of curiosity, I also measured the 7mm axles of my Roll-line Dance plates and found that the 627 bearings are an incredibly close match within 0.01mm!, for this reason my rink says there is less need to go to the trouble finding spacers that fit the wheel-hub design)

QUESTION: What is the reason they donít provide a better fitting axle on inlines?

I also noticed that at the threaded end of the axle there is an extended small area unsupported, that really should be to the axle diameter tollerance (i.e. close to 8mm).

Powerslide axle (on Alpha frame) approx. 2.39mm
Seba axle (on IGOR Pro Frame) approx. 4.40mm (over half the width of the 608 bearing!)

Iíd appreciate comments and anyone who has noticed this. There is a heap of info on bearing spacers, but I feel no one has really covered the question of speed-axle design and functioning.

Thanks for reading.


Your bearing spacers need to be the correct size, and you can put a good amount of torque on the axle bolts to lock the frame, inner races and the spacer into a virtually solid tube of metal.

Most of the time there will be minimal or no drag. But sometimes the spacer is too small, and causes a binding condition, or too big and causes the wheel to wiggle laterally on the assembly.

The OD of the axle is not as important as you would think. However there are ways to make a sleeve from very thin stainless steel shim stock.

If you want a super firm setup this is what you need to do.

1. Make sure you have correctly fitting spacers for each inline wheel. Test fitting and inspection is essential to ensure compression does not cause issues with free spin, which could reduce the life expectancy of a bearing.

2, lightly sand the outside diameter of the bearings you are going to use as well as the hubs of the wheels.

3. Apply blue loctite with a q tip to the bearing bores and the bearings OD. Press in and allow to cure for 24 hours before use.

4 install the axles with blue loctite on the threads as you normally would,.. well in your case, actually put a good snugging on them. Keeping them barely(threaded in finger tight) in there can cause more damage than tightening them a little hard.

Plastic hubs are notoriously poor at keeping a bearing seated, even when new during toe/wheeling tricks on inlines. That's a lot of leverage. The loctite will greatly help keep things fixed in place which will really firm things up.





Quote:
Originally Posted by bjvircks View Post
The most usual reason for small diameter is to allow a larger manufacturing tolerance range. Without going into all of the specifics, holding tight tolerances mean higher cost, larger tolerances are lower cost.

This is why ABEC ratings are important.



In the 'speed' section there have been a couple extended discussions about axles. (a couple years ago or more)

I have a bit of an idea as to why the end of your axles are relieved... It could be to allow clean tool runout during the thread cutting operation. Again... a long relief means easier machining which means lower cost. But, without photos it is tough to guess well.

I would not be concerned with the reliefs on the hardware that much.
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Old March 19th, 2018, 05:28 PM   #4
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Last edited by wornoutwheel; May 15th, 2018 at 01:54 PM.
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