Differences of metric thread pitches

[mart]

I didn’t realise there was a difference of pitches with metric threads. I was thinking it was just A/F and older stuff. Apparently there is course, fine and extra fine on metric threads. The thread angle is 60o. The thread depth is 0.614 x pitch.

This kind of messes up my plans a bit. I wanted to build a cycle trailer using one length of 10mm threaded bar with 10mm cones on for an axle, instead of the two separate 10mm cycle axles. I wanted to avoid the extra frame work supports for the wheels. The intention had been to just build a small rectangle chassis from some 20mm box section that I have in the garage. Drill a hole in each side and put the threaded bar through and use locknuts as it enters & exits the box section.

Anyone know if it’s possible to get threaded bar that is the same pitch as 10mm cycle axles? It has to be the same pitch so I can screw the cones on to hold the bearings in place.

 

[BrokenBiker]

do you know the pitch? It is possible to get any form of metric pitch as threaded bar, just harder to find the fine threads

coarse is the standard thread pitch range used for nuts and bolts

 

[hotrodder]

If the axles are 10mm as long as they aren't Campagnolo they'll be 1.0mm pitch. They also exist in 10mm x 26tpi (crazy Italians only) and 3/8" x 26tpi. 1mm pitch = 25.4tpi
The rear derailleur is always 10 x 1.0mm pitch so if the spindle screws into that you're golden, type '10mm metric fine threaded bar' into the search engine of your choice

Bear in mind that in the old days of the multiple freewheel there was upto about 2" of unsupported axle outboard of the bearing. VERY easily bent (and axles aren't mild steel or stainless, they're chromoly usually) which is why cassette hubs were invented- moved the driveside bearing closer to the dropout to reduce the bending moment

 

[BrokenBiker]

also, running the bar through a drilled whole with no bearings is just going to cause grinding and alot of wear i would think. with weight on the axle i would think the bar would essentially part off where it enters the box section

 

[Pete.]

Threaded bar has about the same strength as soggy tissue especially, the 4.8 grade stuff you get from diy shops.

 

[GrahamGKD]

Bear in mind that in the old days of the multiple freewheel there was upto about 2" of unsupported axle outboard of the bearing. VERY easily bent (and axles aren't mild steel or stainless, they're chromoly usually) which is why cassette hubs were invented- moved the driveside bearing closer to the dropout to reduce the bending moment

I remember those old ones well - I had a least two solid spindles break which is a bit of a show stopper really - either walking home or finding somewhere (pre-mobile) to phone for a lift! No such problems since I have been using cassette hubs.

Threaded bar has about the same strength as soggy tissue especially, the 4.8 grade stuff you get from diy shops.

I know what you mean - you can get high tensile studding from a fastener supplier but I'm still not sure whether it would be stiff enough - I guess it would depend on the load on the trailer?

 

[BrokenBiker]

I personally would use hubs on either side of the frame, with bearings and proper spindles

 

[pedrobedro]

Drill the threads out of the cones and use two nuts to hold them in place with locks.

 

[mart]

also, running the bar through a drilled whole with no bearings is just going to cause grinding and alot of wear i would think. with weight on the axle i would think the bar would essentially part off where it enters the box section

The bar (axle) will not be turning. It will be held firm with lock-nuts as it goes through the box section. OP last line , the bar will have cones on to hold the bearings in place.

Thanks for advising that any pitch of metric size bar is available. I didn`t know that. I`ll try to find out somehow what the actual pitch of the cones are.

 

[mart]

Drill the threads out of the cones and use two nuts to hold them in place with locks.

I like the sound of that idea as a last resort. I guess it would give me more options of cone size lol. I didn`t think of that one.

 

[CompoSimmonite]

Don't forget there is also Cycle Thread
http://en.wikipedia.org/wiki/British_Standard_Cycle
http://www.motalia.com/Html/Charts/cycle_chart.html

Paul H

 

[hotrodder]

I`ll try to find out somehow what the actual pitch of the cones are.

Like i already said as long as the hubs aren't made by Campagnolo (it'll be written on them somewhere if they are) then if they're 10mm OD they'll be 1.0mm pitch which is the same thread used to bolt a rear derailleur to the frame
If the OD is 3/8" (9.5 mm near as damn it) then they'll be 26 tpi

You'd probably be better off using wheelchair hubs/complete wheels for the trailer, they're designed from the outset to be supported (in single shear) from one side only on a stub axle and as such typically use a larger diameter axle, IIRC 1/2" dia 20 tpi. The axles are very unlikely to be soft mild steel though, be something (chromoly etc) with a higher yield strength so they don't bend if someone sneezes while sat in the thing

How much weight is this trailer gonna be lugging?

 

[nickk]

Threaded bar has about the same strength as soggy tissue especially, the 4.8 grade stuff you get from diy shops.

you can get h/t bar aswell.

 

[MattF]

Threaded bar has about the same strength as soggy tissue especially, the 4.8 grade stuff you get from diy shops.

It's definitely not the strongest of stuff, is it. Its flimsy softness does come in handy on occasion though. Made an extractor for a generator rotor out of threaded rod quite easily years ago, due to the fact that you can literally bend it by hand and just showing it a file practically makes it lose half it's width within seconds.

 

[Pete.]

you can get h/t bar aswell.

Yeah Macalloy bar I have used for temporary works. Wouldn't be something the OP would go out and buy though.

 

[mart]

[quote
You'd probably be better off using wheelchair hubs/complete wheels for the trailer, they're designed from the outset to be supported (in single shear) from one side only on a stub axle and as such typically use a larger diameter axle, IIRC 1/2" dia 20 tpi. The axles are very unlikely to be soft mild steel though, be something (chromoly etc) with a higher yield strength so they don't bend if someone sneezes while sat in the thing

How much weight is this trailer gonna be lugging?[/quote]

Ah yes wheelchair wheels-that never ocurred to me. I`ll look in to the "availability"

The trailer won`t be carrying a great deal of weight. Whatever is on will have to be pulled by my leg power as I cycle along. I guess max load wt will be a 4 stone bag of manure, plus wt of trailer.

 

[mart]

Yeah Macalloy bar I have used for temporary works. Wouldn't be something the OP would go out and buy though.

Someone else that knows me

 

[Wendelspanswick]

I come across complete wheelchairs in skips quite often, they quite often come with quick release hubs. There is a set on the 'high speed' go-kart I built for the kids. You press a ball in the end of the stub axle and the hub complete with bearings slides off.
I can take a picture if you want?

 

[mart]

Hi Wendel,
yes I`d like to see a pic. I am guessing that the quick release mechanism works in the same way as the system on this cycle trailer (video) ,although I`ve not actually worked out how it operates inside the hub. Would probably need to see it up close in person. These "Carry Freedom" brand trailers being demonstrated by Jack Dee`s brother are 200 quid!!

 

[mike 109444]

Probably find the pin he pushes allows a ball bearing to drop into a grove in the sprung pin (think of the ball bearing on a 1/2 socket set)