drive sprockets

[manofaus]

I have an old excavator that is going well apart from the undercarriage. I have got some new tracks for the old girl and was looking for some drive sprockets to suit. One sprocket is worth two tracks!! Any how I have drawn up and priced getting some laser cut. Just need to know if anyone knows the material that they make them out of. I have a price of 120 dollars using just 250 plate so thats pretty cheap considering the cost of a pair of tracks is around 15oo dollars. any ideas?

 

[Big Kahuna]

Well 4140 pre heat treated would be my choice, I've been doing Tool & Die work for close to 30 years and when I get a sproket or gear to rework it's not rock hard and cuts like 4140, you want toughness not hardness so I'm thinking 4140 with a Rockwell on the "B" scale of about 50 is a good choice, plus it lasers very nice.


Big Kahuna



http://4140steelplate.com/4140_Plate_Logos/4140_Steel_Plate_Logo.jpg

 

[lsmurphy]

Is rebuilding them with weld a possibility?
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[manofaus]

well the place that gave me the quote only has 250 plate in stock. They can't get 1045 and 4140 would mean I would have to buy a sheet.. They are only 300mm in diameter so i could get 24 cut out of one sheet!!! But I do about 100hrs a year on the digger doing landscaping so not really viable. I might just get them cut and suck it and see.

Re welding them, if I was at my last place of work thats exactly what I would do!! I would then re cut them in a mill with a generating turn table, but alas I don't have that option any more. The old moving it to china put an end to that!!

 

[Dave_eng]

My poor man approach may be a solution for you. First I find a place which sells sheets of 4140 and ask them who buys it then go to those people and see if they will sell you what you need. Often they have left overs they are happy to get rid of for more than scrap prices.
Dave M7040