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View Full Version : RFQ: Parts for hand ergometer (exercise bike)



irving2008
10-08-2013, 07:42 PM
Following on from the project thread (www.mycncuk.com/forums/project-showcase/6234-hand-ergometer.html) 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 :biggrin: ).

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.

93879392

blackburn mark
10-08-2013, 08:31 PM
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
10-08-2013, 08:44 PM
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
10-08-2013, 09:37 PM
eg gears, if the 3D printed ones aren't up to the job..

:culpability: 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
11-08-2013, 04:34 PM
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
11-08-2013, 08:45 PM
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?

chopper12
11-08-2013, 11:01 PM
ok not a problem should be less then 3 weeks, got some 6082 bar ends at work that can use if 6082 is ok?
will need some extra dimensions on the boss as cannot open the .dxf files
hope this helps

JAZZCNC
11-08-2013, 11:44 PM
Just seen this I can help if needed. . . . . just let me know. Got some stuff here if needed

PS: Can do them Wed if that helps.!

irving2008
12-08-2013, 02:05 AM
@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
12-08-2013, 02:38 AM
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
12-08-2013, 01:33 PM
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
12-08-2013, 08:23 PM
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 :biggrin:

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.

JAZZCNC
12-08-2013, 09:09 PM
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 :biggrin:

No problem if you want it from Solid Irving I can sort that, thou it will mean a slight delay has I have to get from a mate.

irving2008
12-08-2013, 09:26 PM
No problem if you want it from Solid Irving I can sort that, thou it will mean a slight delay has I have to get from a mate.

Prefer the tube approach as less inertia as well.

Whats your view on 1 v 2 clamp bolts?

Updated drawings attached. I've only taken the radial slot down to the top of the bearing, think that'l give enough movement?

9422

mekanik
12-08-2013, 09:50 PM
If made from solid you could place one bearing in the centre of the handle and one @ the end

irving2008
12-08-2013, 11:21 PM
If made from solid you could place one bearing in the centre of the handle and one @ the endMy original design was like that but with a bearing insert at the far end of the tube, means a longer axle of course. But none of the commercial units are like that as they offer a range of handle shapes (i.e. bent tubes) for different disabilities so really I'm copying a tested approach.

mekanik
13-08-2013, 12:24 AM
Understand now but if you do not intend to add various extensions your first idea is a better/stronger design,also you would not need the pinch bolts and the slot that is going to weaken the assembly @ the point of most strain, making a shaft with a step to locate the bearings so they are captive on the shaft. if that makes any sense, unfortunately i am not proficient with sketchup as i could better explain with a drawing.
regards
Mike

JAZZCNC
13-08-2013, 06:46 PM
Prefer the tube approach as less inertia as well.

Whats your view on 1 v 2 clamp bolts?

Personally I'd have gone for solid and let me take the weight out of it by boring.!

Regards clamps bolts then probably 2 has it will clamp more even. How many bearings are you planning on using.?
Also the specs for 6900zz are 22x10x6 and if this is being assembled like I think (see pics) then you have allowed for 2 bearings @8mm is this correct.?
See pic6 and you'll see what I mean with 6mm bearing and 4mm spacer between, it leaves shaft sticking out.!

Let me know if I'm wrong and if this is the final drawing.

cheers
Dean.

irving2008
13-08-2013, 08:06 PM
Dean,

If you prefer to machine from solid and dont mind the wastage feel free :biggrin: I went for the lowest cost approach.

When you say 'shaft sticking out' I assume you mean the inner end of the axle? Thats why there are 2 spacers, the second goes on the end of the axle and a standard M8 nyloc nut & washer bears against it. I did it this way as in the past i found a M8 nut is too large and fouls the bearing outer race (da max for bearing 12mm, A/C for nut is 15mm) and turning an M8 washer down to 12mm is fiddly.

But if you have a better solution....

JAZZCNC
13-08-2013, 09:21 PM
Dean,

If you prefer to machine from solid and dont mind the wastage feel free :biggrin: I went for the lowest cost approach.

Ok will do not a problem just small delay on material, which I've sorted. I Should have material for weekend so will do it then.


Thats why there are 2 spacers,

Ah ah my mistake didn't see x 2. . . . Lol . . . . Thou think it better to space the bearings far apart has possible so I'd be inclined to make a washer, so I'll do that if you don't mind. I'll make wider spacer and turn a washer down, turning washer down is easy enough so no problem.

Like this. 9440

irving2008
13-08-2013, 11:54 PM
That works for me!

Those renderings are great, really helps to visualise things. What are you using? Sadly there's nothing that runs on Android that does that.

I'll post other drawings tomorrow, need to review them to see if I can simplify them.

mekanik
14-08-2013, 10:35 AM
[QUOTE=irving2008;47875]That works for me!

Those renderings are great, really helps to visualise things. What are you using?

second that jazz, very impressive.

JAZZCNC
14-08-2013, 11:06 AM
That works for me!

Those renderings are great, really helps to visualise things. What are you using? Sadly there's nothing that runs on Android that does that.

Yes 3D models are great for showing visually unfortunately software to do this quickly and easy is not cheap. These are done with Solid works and it's bloody expensive fortunately I have it thru business so effectively tax mans bought it or should say not getting it. . .Lol

JAZZCNC
15-09-2013, 10:55 PM
Hi Irving,

Nearly done mate had loads of problems with Lathe and my dosy mate bring me wrong stuff.!! . . . But here's a couple of pics to wet your appetite. Just got flats to put on pin and whip crank up on CNC machine then done.

101361013710138

Cheers
Dean.

Clive S
15-09-2013, 11:55 PM
Very nice Dean, how did you do the split to make the clamp bit? ..Clive

JAZZCNC
16-09-2013, 12:29 AM
Very nice Dean, how did you do the split to make the clamp bit? ..Clive

MAGIC.!!. . . . . . . Or . . . 1.5mm end mill in cnc machine. . .Lol

FatFreddie
16-09-2013, 12:08 PM
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.


Let me have the drawings for the gears if you have them (and still want them printed) - got a bit of spare time at the moment (but don't tell my boss that :-) ).

irving2008
16-09-2013, 12:17 PM
Dean

Sorry I missed the update, those look amazing! Can't wait to see them in the flesh...and I am very grateful...

Not been great last few days so haven't updated rest of drawings but will do so later today I hope.

irving2008
16-09-2013, 01:06 PM
Let me have the drawings for the gears if you have them (and still want them printed) - got a bit of spare time at the moment (but don't tell my boss that :-) ).

Hi,

Thanks - I still want to go with an epicyclic gear in the long run but the ratio I need to be safe on the design is nearer 4:1 rather than 3:1. So I've decided to go for a pulley/belt approach for v1 of this as was struggling to make it all fit plus the axle was getting increasingly complex - I need to prove the rest of the mechanism first.

I will revisit the epicyclic version in Mk2 as its neater overall, once I'm happy 3:1 will work.

Thanks for your efforts so far....

FatFreddie
16-09-2013, 01:46 PM
Thanks for your efforts so far....

No problem, it's been interesting.

Let me know if you need anything printing for Mk1 (pulley covers etc).