and so it begins......

[davidbooth1991]

Hi all I've been away for a little while. I will be continuing the kart next week. There's not much left to do just pick up my engine, fix the seat, extend my axle, and find a way to attach the axle to the frame i may well have to weld the disc brake and sprocket on but I don't know yet. Stay tuned guys.

 

[firemanjim]

Whaaaa? Weld? You dont weld anything to an axle..... There are too many ways to mount stuff on an axle besides welding.....
NEVER weld anything to your axle.......

 

[OzFab]

You missed a bit, let me fix it for you...

NEVER

EVER, EVER, EVER, EVER, EVER, EVER

weld anything to your axle.......

 

[firemanjim]

 

[davidbooth1991]

Just hold on a minute while I get my crash helmet................

I know there is a certain speculation that welding to an axle isn't really the best idea and as fabricator / welder myself I'll be the first to say that it is in fact properly not the way forward.

However my axle isn't keyed, it has splines machined in as do the disc, sprocket and wheels. My original plan was to drill out the splines on the discs and fabricate my own hubs, drill through the axle and bolt them together. I need to get a vernier and gauge my axle as my axle is said to be 30mm however going by experience it won't be. I understand that welding to an axle can create a lot of different problems if not done and treated correctly ... heat distortion, fracture the weld obviously is porous so that's not the best. Does anyone have a funny story about welding an axle.

Once again thanks for the help
You guys are legends

 

[davidbooth1991]

Here are some pics of my axle and what I'm doing...

 

[OzFab]

Besides the obvious heat damage, distortion, fracturing, etc problems associated with welding axles, the #1 problem comes when attempting to disassemble said axle if/when necessary...

Personally, I don't have any funny welded axle stories because I've never done it, as (I assume) most of us haven't but, I do remember one case where a kart was built with a centre bearing (for added support) &, as a result, the axle couldn't be removed because the sprocket (or something) hit the bearing retainers, which were enclosed...

 

[davidbooth1991]

So I just got the vernier out and my axle is 30.17...... I need 29.75 ish. So ill have to turn it down in the laithe. Once I've done I'll bolt on the pillow blocks and then I can sort sprocket and brake and get the engine lined through. Stay tuned guys were nearly there

 

[davidbooth1991]

I have just got to get this done now ADHD HAS TRULY SET IN. !!!!!!!!. If I can provide anyone some advise that wants to build there first of sometching BUY SOME PLANS. Or at least think ahead slightly.

 

[MrBracket]

Keep fighting that ADHD... I didn't start with much of a plan when building mine either.. It just sort of evolved as I went. You learn a lot in the process, your next buggy will benefit from what you learn on this one.

 

[davidbooth1991]

Thanks for the motivation Mr bracket ....

It's not so much ability to make it. Its ability to spend money on it. Lmao.

I had too have a week off because I started to cut corners and I started getting anxious and sloppy. Rushing it rather than taking my time
I also think that because I only get half an hour a day ( I build this in my lunch break ) I tend to rush so that I can see I've done something with that half an hour.

I guess I'll have a sit down and restratigise. I'm almost done anyway and than I'm sure it will be worth the wait

 

[OzFab]

There's an old saying; "hasten slowly". As soon as you try to rush, that's when things go pear shaped. I know the feeling but, you need to fight the urge to hurry...

 

[davidbooth1991]

Thanks for all the advise guys

I guess it's always worst when your nearly done.

 

[davidbooth1991]

laithe advise please......

So......
I need to turn my axle down to slide inside my 30mm bore pb bearings. Does anyone how how much I should take it down to. I have turned stuff down and threaded bars and stuff but only to learn how to use the laithe.. I was thinking 29.75ish??? Obviously I'll measure the bearing first.. Thanks a lot guys..

 

[moose]

That seems like alot. I would bring it to size (30mm, if thats what the bearing measures), then try the bearing. If it doesnt fit (it might), take the smallest cut you can, just *touch* it, moving at a reasonably slow rate(tool travel speed). Use ebony cloth to smooth the shaft after. I would be surprised if it took more than a couple cut-check iterations. Resist the urge to hammer the shaft into the bearing.

Goodluck!

 

[moose]

http://www.skf.com/group/products/b...mer-block-units/internal-clearance/index.html

SKF has some clearance tables that would suggest that the shafts should be exactly to size. Take off that 0.17mm (or whatever) carefully.

... also if you measure 30.17mm, is there a chance that its actually 1 3/16"? I guess weigh the cost (time/money/aggrevation) of machining vs cost of new inch-bearings.

 

[davidbooth1991]

Hey moose.


thanks a lot for the help and advise you clearly know more than me. The table on skf really helped me out. I'll measure the bore when they come and take it from there. I don't think I'll turn down the whole length of axle, just down to where the bearings sit in from the end ( unless you know a good reason why I should turn the whole length ). Once again thankyou very much pal.

 

[moose]

No problem, happy to help. I looked back at your axle, and I am a little confused... Are you re-using the disc and sprocket that are on the axle? Instead of turning the shaft down, I would tend to reuse all the existing connections and simply get the Inch bearing size you need (if shaft is 30.17 as you said)

As far as having steps in a shaft, it will be a stress concentration, but if we are talking 0.17mm step, I wouldn't worry about it.

I would be more help if I understood what you are trying to do a little better though.

 

[OzFab]

That seems like alot. I would bring it to size (30mm, if thats what the bearing measures), then try the bearing. If it doesnt fit (it might), take the smallest cut you can, just *touch* it, moving at a reasonably slow rate(tool travel speed). Use ebony cloth to smooth the shaft after. I would be surprised if it took more than a couple cut-check iterations. Resist the urge to hammer the shaft into the bearing.

Goodluck!

If I may, you mentioned slow tool speed but, IMO, a high chuck speed will give a finer, cleaner cut...

 

[davidbooth1991]

Ok guys I really appreciate all the help and advise. Moose....
My axle is splined to take the discs, it's 29mm after the splines. I'm extending it with 30mm bar to get the length I need to turn down the centre piece to get my bearings on. I'll take some more pics and go in to more detail if you need me too. Im going to turn down about 250mm in from each end as that is where the bearings will sit. Do you think this is the right way to do it guys????? Thanks again.