Bearings for wheels

I have bought the e book for the PYRTE traction engine & just before I head for the MEX at Brooklands to start looking for materials I made a summary of some of the materials in a more organised list. Then I started looking on line to get an idea of prices

When I got back up off the floor I began to wonder about things like the bearings for the wheels. I have already sourced the steel for the wheels but the Phosphor bronze for the bearings seems expensive & it has occurred to me that if I took the middle out of some old ballrace bearings & mounted them within steel carrier parts I would have something that would wear every bit as good as PB- or would I? in fact the complete bearing could go in the front wheels & if it worked the same could go on the rear & i would only need to lock the bearing to lock the wheel. I am not really worried about the look , more about getting a working model

The problem would be getting the ballrace mounted into the carrier true to the wheel & axle but is that is no different to boring the hole in the PB correctly - just a little harder ?

So am I thinking out my rear end or can I save some bucks for a bit more time spent ?

Steel on steel should last, as a bearing material, but you need to be certain that no water will ever get anywhere near it ... As your mileage is likely to be low, why not brass instead of bronze?

Cheers, Tim

PB is not that expensive is it? Have you looked into getting cored PB with the hole up the middle so you are not paying for what will soon become swarf? Or Oilite bushings, made of sintered bronze granules etc to a finished size. They are usually not too expensive. I have also found that buying pre-made bronze bushes from my bearing supplier can be cheaper than buying bronze bar to make them myself. They come in a range of standard sizes.

You won't have much luck trying to take a hardened steel inner race from a ball bearing and running it as a bushing on a steel axle: the hard steel race will wear out the axle pretty quick.

You could fit ball bearings as complete units if there is room in the wheel castings or whatever to accommodate the larger outside diameter of a ball bearing when compared with a bronze bushing.

Me, I'd stick with the design and scope around for a cheaper supplier of bronze.

Also, you probably don't need full-on phosphor bronze. You may find a leaded bronze like LG2 grade, aka gun metal, will work fine for your purpose and may be cheaper too. Phosphor bronze is more often used for high speed application in conjunction with hard steel shafting.

Edited By Hopper on 16/09/2016 10:21:26

ME tends to be a long game so it pays in the long run to look out for useful cheap bits and sources as you go through your ME life

Scrapyards and offcut auctions are the cheapest route. Occasionally you get lucky and find a bar of bronze lying in the street (yup, no kidding, a 12 inch long 1 inch thick bronze bar just lying in the gutter)

The alternative is to buy it all instantly when you need it and pay an inevitable premium

For the rear axle, you may be able to use ball bearings in pillow blocks, but I believe your axle will be about 3/4" diamter so (good quality) ball bearings that large will not be particularly cheap either. Depends on where you shop around etc as Ady1 said above.

Edited By Hopper on 16/09/2016 10:19:19

Edited By Hopper on 16/09/2016 10:19:40

Compared with the overall cost of making the model, buying a pair of top branded bearings should not put you off.

^ True that. I imagine copper boiler tubing, silver solder and the necessary fittings will make wheel bearings seem cheap.

Sam, I would not use steel on steel for your bearings, I was taught never to use similar materials for this type of assembly. You will inevitably finish up with water in the bearings one way or another. Neither would I use brass if you intend to run it. I am not familiar with the design but looking at the video it is not a big engine, so using commercial bronze bushes in a housing is the most economical way to go. What size do you need? you may find someone on here has just what you need in their scrap bin and would be happy to help a beginner.

Chris Gunn

If the spokes are not soldered into the hubs you could save the steel for something else and make the hub from cast iron and not bother with a bearing.

Another option would be to look at oilite bearings, they are often a lot cheaper than a bit of bronze that they could be cut from, probablt a couple of quid each on tat size engine.

I had never heard of oilite before & now I have googled it I am pretty certain that I can pick these up dirt cheap. I had an account at a bearing supplier for 20 years & they have since opened a branch 5 miles from me. Account is no longer open but I can still get bearing items very cheaply so thanks for that tip . I will drop in & have a chat next time I go past their depot.

If you do use Oilite bearings, have a bit of a read up on them. As you buy them, if you put them on the shaft they are intended for, they will be quite loose. There is a correct dimension for each size of bearing, this will close the bearing to it's correct size. Don't ream the bush if it is too small, polish the shaft down to fit. If you ream the bush, it closes the pores in the sintered bronze, stopping the oil from lubricating the shaft. These bushes are often backed up with a felt pad to retain extra oil.

Ian S C

Many people don't realise you CAN machine Oilite bearings, but best bored with a sharp single-point tool., Oilite recommend using carbide. Interestingly you can use ball sizing - that is force a hard ball bearing though to open it up dead to size. This is their advice:

Best Machining Practices
There are a few basic machining practices required to optimize retaining surface micro-porosity and the self lubricating properties of Oilite® bearing materials.

Cutting tools must be sharp. For this reason, carbide inserts are highly recommended since they hold a cutting edge much longer. This preserves the open-pore structure from which oil can flow freely. A dull tool will smear the pores, greatly reducing the self-lubricating qualities of the material.

Turning: Cutting Feed Rate: 0.002-0.006 IPM
Speed: Oilite® Bronze 375-500 SFM
Speed: Super-Oilite® 250-500 SFM

Roller Burnishing is an excellent choice to modify an ID slightly. Ball sizing can also be used on the ID effectively for final sizing.

Honing and grinding are never recommended on Oilite® bearing materials. Using these methods on any surface which will become the bearing surface will introduce grinding media and could easily smear the bronze pores sealing the micro-porosity.

After extensive machining, bearings should be re-impregnated with appropriate / specified oils. Vacuumed impregnation is recommended. If bearings were not lubricated prior to machining and if cutting fluids were used, that medium must be removed prior to any impregnation of the oil selected for the application. Your authorized distributor can provide oils for re-impregnation after machining.

I was taught to use flood coolant when machining Oilite as heat from machining can leach out excessive oil. Mind you, I have learnt something else from Neils post in that you CAN re-impregnate the stuff when necessary.

Rik (I was about to put a remark here but it suddenly reminded me of Oubaile who I have not seen post here a while - are you still with us Geoff?)

On line suppliers have good web sites for bearings. I use "Simply Bearings" a lot when re-bushing motorcycle girder forks or old ground keeping equipment. Price comes down as quantity goes up.

Just a reminder of another bearing alternative, white metal

For "Oilites", not everyone has Vac impreg equipment, but most have access to a small tin containing oil with the bush immersed in it. Heat gently, no need to generate smoke and allow to simmer, then let it cool completely with the bush still immersed. On older bearings, they benefit from a prolonged soaking in a suitable solvent and drying before the boil in oil treatment.

Regards Ian.

Now we're HSE'd to glory, the old "Suitable" solvents were Carbon Tet or Trike.

You can still get Carbon Tet, although it's now known as Perchlone. I got some by post even. It wasn't cheap. You might be able to scroungs some from a dry cleaning firm.