Alternatives to bearing bronze

[Chicken]

Hi all,

I'm currently bulding a hit and miss engine mostly my own design and fairly large with 100 cm³.
It's mostly built out of scrap iron and scrap aluminium and fairly cheap.

But basically the most expensive stuff on this engine is the bearing bronze required for the crankshaft and connecting rod bearings.

I was wondering if there are suitable replacements for this? I know that some aluminium alloys can be used as bearing material, but which one?
I was also thinking about babbitt bearings. I think this should also be very easy by using a steel case and casting the babbitt metal into it. I can get a very hard babbitt alloy composed of 60 % lead, 30 % antimony and 10 % tin for less than 10 euro/kg. Is this useable?

Thank you for comments!

Best regards,
Alex

 

[Niceonetidy]

You could use cast iron for the bearings, that an work well at moderate rpm, well lubricated!

 

[mrspoom]

yes, that would be good to use. I re-babbidted a bearing for my old lathe. The hardest thing I had to deal with was the damming material; as the babbit will run like water when its ready to pour and your shell is hot. I bought some stuff on the internet called "babbit rite". Having never poured babbit before it was learning experence for sure.

 

[Jasonb]

Apart from the cast iron mentioned above have you thought of buying hollow cast bronze as you are not paying for the bit in the middle that will end up as swarf.

You could also size it to use off the shelf sintered bronze (oilite) bearings, the half scale Domestic I made last year spec'd them for the main bearings, think they cost me about £2.00 GBP

J

 

[Chicken]

Sounds interesting!
I have plenty of cast iron left, but will it really do well for the conrod bigend bearing? I was planning to install a wick type lubricator wich should continuosly feed some oil to the bearing. Is this enough for cast iron?

 

[Rivergypsy]

Oilite is fine, but not to be machined afterwards, otherwise you'll close the pores of the material and stop it working correctly.

If you're not running it regularly, have you thought about brass, or (to tempt discussion) IGUS bearings? ;o)

 

[lensman57]

Hi,

I am with Jasonb, if you can redesign the engine go with Oilite, it is better than bronze and will last a life time. Cast iron is the last choice, for low rpm engines but it need to be the right type, SG I think but I am not 100% sure.

A.G

 

[Dave Sohlstrom]

I've cast a lot of babbitt bearings. I used a material with the slang man of Monkey Sh!t. I think it was originally designed for pluming work or electrical work but works great for sealing things up so you don't get babbitt all over the place and none in your bearing shell.

Dave

 

[pkastagehand]

have used Delrin for some of the bearings. Not sure if it would hold up very long or not in this application. Pretty cheap though. If it does wear out then replace with something longer lasting. Let us know if you try this route. Having empirical data would be good.

Paul

Hi all,

I'm currently bulding a hit and miss engine mostly my own design and fairly large with 100 cm³.
It's mostly built out of scrap iron and scrap aluminium and fairly cheap.

But basically the most expensive stuff on this engine is the bearing bronze required for the crankshaft and connecting rod bearings.

I was wondering if there are suitable replacements for this? I know that some aluminium alloys can be used as bearing material, but which one?
I was also thinking about babbitt bearings. I think this should also be very easy by using a steel case and casting the babbitt metal into it. I can get a very hard babbitt alloy composed of 60 % lead, 30 % antimony and 10 % tin for less than 10 euro/kg. Is this useable?

Thank you for comments!

Best regards,
Alex

 

[Chicken]

Currently I like both cast iron and the babbitt solution. I won't go for delrin, I think this is not suitable for IC engines.

my current favour is the babbitt as I guess it will last much longer than cast iron and will be less sensitive to lack of lubricant? true? I already have a idea for the casting to avoid spilling the molten babbitt everywehere.

 

[idahoan]

Babbitt makes a beautiful low friction bearing; I find the casting and finishing process quite enjoyable.

You can check out my Pacific build; starting about post #44 is where I poured the bearings.

http://www.homemodelenginemachinist...ne-morrison-marvin-castings-17832/index2.html

Can someone explain to me why Oilite is better that plane old 660 bearing bronze? If you plan to grease these bearings it seems to me that the Oilite would be a waste.

Dave

 

[Chicken]

That's a very nice build!
It looks like your just pouring the babbitt into the blank casing. I thought it is necessary to apply a small coating of tin prior to pour the babbitt or will it also stick to the bare iron?

 

[Till]

Your local agricultural machinery store has all kinds of bushings in a wide range of materials and size.

 

[mrspoom]

I've used delron in the past, works good for awhile but it will chalk up, dry out, and get brittle if exposed to sun light.

 

[mrspoom]

just thinking; you could make a mold and pour babit in making the whole bearing babbit. Just don't go crazy tightning the bolts.