Which plastic is more durable?

[Chillimau]

I am thinking about fabricating a replacement roller for my center mount mower. Current roller is plastic of some sort but has worn out. New one is $30.00 for a 2.50" dia x 7" roller. I can buy a 2ft piece of nylon 6/6 for $38.00 or UHMW polyethylene for $18.00 and make three of these rollers for around the price of one. Any ideas as to which plastic might be fairly durable? I know this is only $30.00 but it shocked me the price for a wheel/roller and I can fab this in half an hour.

Gary

[RobS]

The UHMW Poly is a lot "tougher" and much better suited for that application. The nylon will be too brittle and may chip/crack over time. The poly is commonly used on assembly lines for wear surfaces and is also easy to machine. If you really want it to last, sleeve it for the axle bolt to ride on.

Post some pics when you're done [img]/w3tcompact/icons/smile.gif[/img]

[kevincook]

I think the UHMW PE would be too soft for this application and is likely to wear out rather quickly. The Nylon 66 will not be brittle and is actually a very tough material also. The idea in the previous post to PRESS a bushing into the center is an excellent idea but may not be necessary for the Nylon 66. If you leave the mower weight sitting on the UHMW PE roller you will probably end up with flat spots on the roller.

If it was me I would just spend the $30 and buy the OEM part since it should be years before you would need to replace it. If I was determined to make my own I would choose the Nylon 66.

FYI - My degree is in polymer engineering as well as it being my profession.

[rdln]

rollers that go on boat trailers can be had for $6 come in 2.5dia x 9 or 12? for 5/8" shaft. A lot softer than what you want but rollers are not supposed to be in continuous contact with ground.

[djradz]

Gary, not too sure about the material, but I wouldn't expect to wear one out, no matter what it's made of, assuming it's there to prevent scalping. Usually the roller should never be touching the ground unless your on some extremely uneven or hilly land. The use of "check" chains at the front of the mower deck will give you a much more even cut and keep the mower from bottoming out at the front. The roller should be there as a last resort only.

[Chillimau]

thanks everybody, I went ahead and bought the OEM part. Needed a long drill and I didn't have the right size.

djradz, can you decscribe a check chain? My mower is mid mount and has a total of six points where it is attached to the tractor. Two bars at the front of the deck which go to a brackett on the front bumper, two arms which attach near the back of the deck and attach to bracketts around the clutch. The other two points are used to lift the deck and are towards the back of the deck. I will try to post some pics later. I'll check but I'm pretty sure that my roller is in constant ground contact. Last one siezed on the shaft and became flat spotted and will plow thru a soft area.

thanks

G

[Anonymous Poster]

Polymer man..............Get some of that Kraton polymers stuff...........The best there is out there!!!!!!!!!!
Kraton.com

[djradz]

ooops, thought we were talking 3-pt mount. However, on a mid-mount, is the roller really what is supposed to take all the weight?

[Soundguy]

I must disagree in reguards to the nylon.

Many deck wheels on mowers are nylon, or a vinyl product.

One feature of nylon is 'self lubrication'. It is great for bushings and shims. Very machineable, stiff but with some plasticity, and not as brittle as fiberglass.

We use nylon spacers and bushings in our heavy construction equipment, as oem specs. Nylon is fairly chemical resistant, as some polyethelyenes are not. ( specifically hydrocarbons.

Nylon makes a good mate to a polished surface like chrome, brass aluminum and steele. Many high volume ball valves are nylon vs chrome surface contacts.

Soundguy