We bought a 2001 PC220 a few days ago and have got a mechanical thumb on the way. I have had a few people tell me that it is best to plate the stick with 3/8 steel before welding the thumb on. Thumb company says that people do it both ways. This is a machine is gonna be used for farm use clearing hedgerows and dipping ditches. What's your opinions for a newbie?
When I worked for a Komatsu dealer in the early nineties we plated the bottom of all the sticks that got a hydraulic thumb installed. Most got 12" plate that went from the center line of the bucket pin to the center line of the boom to stick pin. I notice later on after I left they had quit doing it. I've never seen a plated stick crack, but saw lots of busted sticks with a thumb. In my opinion I think it is good insurance. Good Luck!
I was told that the older sticks would crack occasionally with a thumb, but newer sticks are a lot heavier. Supposedly they don't need it. I put a thumb on my machine, 2007 volvo 240, Thumb manufacturer would have told me if i had to do anything special before mounting. The thumb came with a huge hunk of plate as its backbone anyway. They gave me instructions on how to weld it on.
you really need need to plate it. When you do, cut some circular holes in the center of the plate at 2-3 locations. This will allow you to weld the plate in the middle of the stick. Otherwise, if it is just welded on the sides, it could pull loose.
My Komatsu PC-120 dosent have any plating where the thumb mounts up. I always wondered if maybe it should. But the machine is twenty years old and there are no weld repairs so I guess it has never been an issue. Maybe on the larger machines its more necessary?
as it was explained to me... the plating was to wrap around the end of the stick to keep the bucket pin from being pushed off. i think it is more important to do so when you have a hyd thumb as you have 2 cylinders trying to push the bucket pin off end of the stick. mine is not plated and there is not any damage, and it used to be a rental machine. i think that if you do a good job welding and dont beat the heck out of the thing you should be fine with out it. just my opinion tho.
I concure with Watglen on this one...the steel is a lot better now then it was back in the 1990's.....Komatsu since has changed venders for the boom segments thst are contracted out for fabrication......but the cost of plates is not the bad compared to the cost of a new boom or down time.....just my 2cents...peace out..
My PC220 I put the thumb on had a large backbone and a welder that knew what he was doing, had no problems at all.
We plate all sticks when we install thumbs at our Komatsus, to us it takes a little more time and a little more material but keeps our customers from having trouble in the future. Myself ive probably installed eight or nine thumb kits on pc200-pc220s.
3/8" go 1/2 " for this size this is heavy duty star on the bottom all the way to the top almost whre your stick boom meets I'v done them many cutt 2 -3 holes like other guy sugested .............. good luck
stick plate Here is an idea short lines onthe ends are stress welds so your stick or plate wont crack you cut holes acordingly where it will be best after know where your thumb will fit Let me know if that you understand cheers all TB IN new year
Thanks for all the advice.
I don't know if I would weld a reinforcement plate all the way up the stick for the thumb?. I would check before installing a thumb if first off has this stick been reinforced with sub plates inside of the stick??. almost all sticks that i have welded a thumb package on have developed cracking on the stick!!. this is caused by not having the stick reinforced internally. Not to say some customers have gotten away with not doing this to there sticks but it will happen one of these days!! Just my own opinion!!! a 1/2 in plate sticking out 2 to 3 inches pass the length of the thumb frame