Thread: Machinist in West Melbourne.

Hi All. I just found this forum from the Woodwork side of things. I didn't realise it went this big. I'm hoping someone can point me in the right direction.

I'm working at a school and some of my students are building a go-kart. It's new for all of us so there is a steep learning curve. Most of my experience is with timber and our other teacher does more with metal. I've had chat with him and the metal lathe we have is too small for what needs to be done.

To attach the rear axle, the plan is to put bearings inside a metal tube and weld that to the frame. The axle then goes through the tube and everything is put into place. What we're trying to do is machine out the inside of the metal tube. It only needs 1-2mm taken off the inside and recessed in about 20mm. I've attached a pic. The tube is 60mm in diameter and 600mm long.

Are there any hobbyists or workshops that might be in the area that could do this? We're in Taylor's Hill. I think this would be a fairly small job but again, I don't have much experience with metal lathes.

Thanks.

I'd rethink the design so it fits your lathe.

Machine a housing on your lathe that suits either the ID or OD of your tube, then have the bearing outboard of the metal tube you're using. To install, press the bearings into your housing and then mount both housings onto your tube, using the axle for alignment. Use Loctite to secure the housings you've machined to the metal tube.

Not only will it then be possible to machine this yourself, you'll finish up with a more accurate end result that will be much stronger. Simply machining the ID of that tube and pressing in some bearings to the thin (and thinner after machining) wall tubing would not be a very good result in my opinion.

If you don't quite get what I mean I can draw a picture to make it clearer. Otherwise look at many contemporary bicycles, the bearing cups sit outboard of the bottom bracket. In their case the bearing cups screw into the bottom bracket, however that is simply to maintain consistency with the bottom bracket thread convention of bicycles. The principle is the same if the bearing cups are simply pressed in/over the housing (bottom bracket in the case of a bike) and then secured with Loctite.

That makes a bit of sense. I'll have a chat with our other teacher and see what we can do.

As far as the pillow blocks go, that was the initial plan. My students have developed the plans (based on other go kart plans) and they made the frame too small to fit the axle they've got. One of them was talking to a supplier that they've got some parts from and he made a few suggestions.

At this point, they're basically experimenting with what they're doing. I'll pass on the ideas and we will see where it goes. Thanks.