CAD Digger Bushings - Brass vs Nylon??

dourobob · Nov 25, 2002

My buddy and I are building a Caddigger 821 and we are now pricing bushings. The Cadplan specs call for 6 brass bushings that are 3 inches long with ID of 1.5 inches and OD of 2 inches. So far the best price we have been able to obtain is about $300 CDN for the set of 6 bushings.
On the MetKit specs they quote nylon bushings and price them at $8 US each or $48US for six. Even with the $$ exchange this is quite a price difference.
What am I missing here? Can nylon really replace brass in this application? What is the life expectancy of one versus the other?
We would appreciate any feedback from bushing experts and/or from anyone who has used either option in building a Cadplans Digger.

Any recommendations on sources of bushing would also be appreciated.

Thanks
Bob

Anonymous Poster · Nov 25, 2002

Duroguy, I can tell you from experience with digging equipment of all kinds and having rebuilt a couple of backhoes that the nylon bushings just do not have the strength to resist 'flowing" out of the bore when great force is applied. This just isn't a nylon application, in my humble opinion. Actually, some commerical hoes don't even use brass but a very hard alloy bushing that works against a hardened pin or shaft. Some of the bushings on the hoe can be greased, and some run dry, like the bucket linkage. It that case, only hardness and tensile strength will survive.

JohnZayka · Nov 25, 2002

Try MSC @1-800-645-7270, or www.mscdirect.com. Reference MSC #35374123, SAE- 660 cast bronze sleeve. Dimensions are 1.50" ID x 2.00" OD x 3.00" long. Price in catalog is $10.29 each. I do a lot of buisness with this company, and they are great.
John

Soundguy · Nov 25, 2002

I'll have to agree with the others. Nylon is going to deform and wear rapidly in this type of environment. Perhaps if they were captive bushings of some sort, maybee.

But as a comparison, the bushings in all of our heavy equipment from the loaders all the way up to the earth movers are brass.

If this is a real small light duty job, for say like a ford 1210, or a yanmar 1500 or something.. or. kubota 2200bx...you might want to try it.. heck.. for 50 $ if it doesn't work, you can always get the brass ones.

Just keep an eye on play on all pins and cylinder ends... but still wouldn't reccoment them for anything over a couple hundred pounds of distribution.

Soundguy

Steven · Nov 25, 2002

You can by brass tubing 2" outside diameter x 1/4" wall thickness, and just cut them to 3" lenths. did not get a price quote but this is one site to start with. <A target="_blank" HREF=http://www.lewisbrass.com/rbt.htm>http://www.lewisbrass.com/rbt.htm</A>

Anonymous Poster · Nov 26, 2002

Er.......not to put too fine a point on it, but in actuality the material that is used in these bushing is BRONZE, instead of brass. They use bronze for it's durability over brass. I think bronze is tin and brass combined........but don't quote me.

hazmat · Nov 26, 2002

CJ, you are right to put a fine point on it. Bronze is the material of choice, not brass for bushings.

<A target="_blank" HREF=http://www.mcmaster.com>mcmaster carr</A> has them for $10.29 also.

One of the OEM's for bushings & bearings is <A target="_blank" HREF=http://www.bostongear.com>boston gear</A>

Here is the catalog page <A target="_blank" HREF=http://www.bostongear.com/pdf/bearing_catalog_sections/bearings_8-17.pdf>bronze bearing pdf</A>

sleepyhollow · Nov 26, 2002

Hi Folks,

Bronze is a combination of tin and copper.
Brass is a combination of copper and zinc.
Hope that clears up any confusion

Sleepyhollow

Anonymous Poster · Nov 26, 2002

Thanks, Sleepy; I've never been able to keep that straight. I have no problem with the four best conductors: Silver-Copper-Gold-Aluminum......Sport-Cars-Go-American....I need to think of something that goes with brass and bronze.

mrcaptainbob · Nov 26, 2002

I used the graphite grooved bronze 1" ID bushings when I made my CadPlan 628. Used the dirt digger to clean out some growth along the pond bank, submerging it in the water doesn't hurt it a bit. Costs a bit more than the others, but I didn't want to visit that area again. I hope It lasts a good long time to justify the effort.

dourobob · Dec 2, 2002

Thanks Guys
Here is what the MetKit folks e-mailed me today

"These nylatron Bearings are molybednum impregnated to lubricate over the lifetime of the bearing. You can also grease them for even longer bearing life. We think they are better than brass and CADplans has approved the substitution for their applications. We think you will be happy with the product. "

Anyone ever used this Nylatron? Experiences - good or bad.

Thanks
Bob

jrlichina · Dec 2, 2002

I have them on my CADDigger and have had no problems. I added zerk fittings to all the pin locations so I can grease them as needed.

DK35vince · Dec 2, 2002

I have been using the nylon bushings from Metkit 3 or 4 years now on my Caddigger.No problems so far !

MossRoad · Dec 2, 2002

These nylatron Bearings are molybednum impregnated to lubricate over the lifetime of the bearing. You can also grease them for even longer bearing life.

These are the kind of statements that crack me up! It will last its lifetime but you can grease it to last longer than its lifetime. Wonder what they consider the lifetime to be?

dourobob · Dec 3, 2002

Wonder what they consider the lifetime to be? 

That is exactly what I wrestle with as well - of course anything will "last its lifetime" and, so will all of us (I am not sure how much grease - or what kind - I need to last longer than my lifetime /w3tcompact/icons/laugh.gif).
I am impressed to hear that Vince has been happy with the Nylatron Bearing performance in his digger over 3-4 years. Vince, I'd really appreciate it if you could tell us the model of your digger and about how many hours a year you would use it. Have you pushed it to its maximum capacity?

I would pose the same questions to jrlichine just for the sake of comparison.

Thanks - this info is really helpful.

Bob

Soundguy · Dec 3, 2002

See though.. they worded that very judiciously... it will lubricate 'over the lifetime of the bearing'..Assumably, once the bearing is worn to a certain point its service lifetime is over. Then what they are saying is that be adding additional lubrication will extend the service life.
They probably should have had the engineer right up the specs, rather than a lawyer.../w3tcompact/icons/eyes.gif

Soundguy

These nylatron Bearings are molybednum impregnated to lubricate over the lifetime of the bearing. You can also grease them for even longer bearing life.

These are the kind of statements that crack me up! It will last its lifetime but you can grease it to last longer than its lifetime. Wonder what they consider the lifetime to be?

jrlichina · Dec 3, 2002

Model 508 used quite a bit for 1 1/2 years.

DK35vince · Dec 4, 2002

Bob,
I have a Caddigger model 710.
It has a gas motor like the model 728,but it will separate behind the seat and can be used on the tractor 3 point hitch like the 708 model.
I usually run it with the gas motor.It digs quite well.
As far as use,I probably have averaged 20-25 hours per year for 3 or 4 years now.(can't remember what year I built it).
You asked if I pushed it to it's maximum capacity-Yes,every time I use it.If it is running I get everything out of it that it will give !
I got the hardened pins,nylon bushings,and the hydraulic kit(hoses, cylinders,control valve,etc.from Metkit )and so far they have worked OK.

KWentling · Dec 6, 2002

Bob: I haven't personally used any Nylatron in my own equipment, but I work in a repair machine/weld shop that does a lot of work for the coal mines. We have one customer that uses Nylatron bushings (we turn them out for them from stock) for the truck box hinges on their 190 and 240 ton haul trucks and they claim they outlast the factory brass bushings 2 to 1!
Now thats some severe service there.

Kim

dourobob · Dec 6, 2002

Thanks Kim
That is pretty impressive. I have ordered the bushings from MetKit. After discussing this (ad nauseum according to my wife /w3tcompact/icons/laugh.gif) with my buddy who's shop we are using to build this digger, we decided to go this route. If they don't last we do have the facilities to change them fairly easily.

Thanks to everyone for their outline of experience sprinkled with an appropriate dollop of skepticism - a pretty good mix I think.

Bob