Parts for hand ergometer (exercise bike)

[irving2008]

Following on from the project thread and some redesign I now need some parts made. Happy to pay reasonable rate for work and materials (given situation it would be easier if you can source them), not looking for charity (but not going to turn it down either ).

The first drawings are for handles & crank assembly, others to follow. Ideally I'd like to get these done within next month. PM me if you can help.

[blackburn mark]

That boss looks a tad short to my eyes for hanging an aluminium tube?

Cant help you on the alli parts but if you can use anything in acetal let me know.

[irving2008]

you may be right.. even if loctited in place? No problem to make it longer though.

And thanks for the offer.... i'm sure there are parts that could be done in acetal... eg gears, if the 3D printed ones aren't up to the job..

[blackburn mark]

eg gears, if the 3D printed ones aren't up to the job..

Ill need plenty of notice as they will be all science to me, Iv only ever cut T2.5 timing belt pulleys thus far.

[chopper12]

hi,
just noticed this thread, what material and quantities and timescale are you looking at?
might be able to make some of the bits in the evenings after work if that helps you out

[irving2008]

hi,
just noticed this thread, what material and quantities and timescale are you looking at?
might be able to make some of the bits in the evenings after work if that helps you out

For all the drawings posted, unless stated, the material is aluminium, some machineable grade such as 6061 but depends on what can be picked up on eBay/etc. As to quantity, 2 off each drawing (i.e 2 cranks, and 2 handle assemblies comprising 5 parts, handle/boss/axle/2xspacer). Timescale, well I need to get exercising, so ideally as soon as possible, maybe within 4 weeks?

[irving2008]

@chopper. Thanks for offer, tho if JazzCNC can do it sooner I might take him up on it. While adding additional dimensions I realised I'd made a slight boo boo in the design which needs correcting. I'm updating drawings and will post updates and some new drawings for other parts tomorrow.

@JazzCNC thanks, sooner is better. As I said above there's a few other parts drawings to come.

With regard to current drawing for handle, is depth of boss (10mm) into tube enough or should I increase to 20mm?

The axial slot on the larger side of the boss is to allow the cross screws to clamp the outer shells of two 10x22x6 bearings. I copied this from an existing assembly which I couldn't dismantle. Will this work or does it need a slot radially where the clamp section meets the 64mm dia, 3mm thick hand guard section to allow the clamp to, well, clamp?

[JAZZCNC]

With regard to current drawing for handle, is depth of boss (10mm) into tube enough or should I increase to 20mm?

Yes more the merrier I think considering the handle is 150mm long thats not much holding it.

The axial slot on the larger side of the boss is to allow the cross screws to clamp the outer shells of two 10x22x6 bearings. I copied this from an existing assembly which I couldn't dismantle. Will this work or does it need a slot radially where the clamp section meets the 64mm dia, 3mm thick hand guard section to allow the clamp to, well, clamp?

Know what you mean and yes it would clamp better if this was slotted.

I'll PM you Email address.

[mekanik]

Hi irving
If i was making the handle assembly i would manufacture from one piece of ally with an interference fit for your two bearings. also make the 150mm length 22mm Dia & then you can fit some proper cycle handlebar covers.I bought that ring gear just to see if i could work out the gear form(probable modular) don't know if the required wheel size will mesh though as the mating components from the hub it came from are rather small.
Take care M8

[irving2008]

Hi irving
If i was making the handle assembly i would manufacture from one piece of ally with an interference fit for your two bearings. also make the 150mm length 22mm Dia & then you can fit some proper cycle handlebar covers.I bought that ring gear just to see if i could work out the gear form(probable modular) don't know if the required wheel size will mesh though as the mating components from the hub it came from are rather small.
Take care M8

Thanks for your input.

I had considered machining it from the solid but thats a huge amount of wastage of a 65 or 70mm bar x ~350mm. Thats over £50 +p&p on ebay to throw 50% away! However if someone wants to provide the stock for free then I'm not proud

Not sure a pure interference fit would be stable enough and all the designs i looked at use a clamp arrangement with either one or two clamp bolts. Two bolts might be overkill tho.

The diameter of the grip needs to be much bigger than a normal cycle handle bar as I cant wrap my fingers that tightly. The 32mm dia is the same size as the one I use at the rehab unit and will be wrapped in bar tape or sleeved with rubber tube heatshrunk on.