To some of the bore masters on here; please give me a word of advice? I am currently doing an excavator rebush and rebuild on my sons 9040b excavator, farm machine anymore, not a front line machine. My question: after getting the old bucket bushings out, I tapped the new bushings in a bit to line up my boring bar. One side is a tad bit bell-mouthed, about .015 runout, other starts with a dead blow hammer and quickly becomes a press fit. Should I go ahead and spend some time over boring and rebuilding the bores for a full press-pull in fit, or go back as it is? I will have to do all the bore welding with wire feed, borewelder is not in my budget at this time. I have the upper bore to rebuild and I know its gonna be a booger!!!!!
As the old saying goes - "Do it once. Do it right." You will always have "what if?" in the back of your mind if you don't.
The problem with the egg shaped bore is that the bushing will not have full contact, and this is likely to cause the bushing to crack and break. If you do it right, you will not have to worry. If it is a low use machine, you may get away with it for many years, but only you and your son can weigh out the risk.
I agree, what should I shoot for as Interference fit when I bore it out? I always heard to aim for a .001 per inch of bore size? and forgive me, I know its metric dimensions but I can't quit my US measurements. dimension is 105 mm or 4.133 inches. and my bore equipment is home made.
here is the bore that most definitely has to be addressed!
Be sure to restore the faces to the original width to prevent the bucket from slapping back and forth. That will make the whole thing last longer.
Just bore them out and put komatsu bushings in there
Jerry is right. The bearing won't be supported in a loose bore and it will have to much pin clearance and it will eventually crack and fall apart making a worse mess of the bore. Have you miked the bearing? Normally a bearing like that will measure nominal plus,say 105.15. The .15 will be the interference the maker wants. 9 times out of 10 bores for bearings are cut to size,in this case 105.00.If the bearing doesn't measure plus on size your rule of thumb,thou per inch will be good.
Are the Komatsu bushings better for wear or are they little bigger so you just bore it a little and put them in?
No need to apologize for us measurements. I refuse to use monkey meters.
Got out and bumped the new bearings back out today and convinced myself that I definitely need to build and bore as you all have said! dead blow hammer and brass drift was it took to get them back out. and one side rocks about .025 back and forth after its about half way out. As I mentioned earlier, all my equipment is home built "mostly from study of what I see many of you using here". I am going to have to either build or buy a facing tool, any thoughts?
I have got a couple of facing heads that will cut out to 3 feet diameter,They cost serious money. For small faces like that I just plunge them off with a 90 deg. cutting tool an 1/8 at a time.
Thats probably my best way to go. I have a couple of ideas that I have to figure out how I'm gonna build 'em, I do get lots of inspiration from seeing ya'll do and get really big dreams though.
Although it's going to need more work I would strongly suggest you put the borer in there first and get the bore from its current egg-shape to circular, however much oversize it ends up being. After welding when you machine it back to size again at least you are taking a pretty much consistent thickness cut off the wall. Also by taking something out of the bore you're also giving yourself some nice clean steel to weld on.
I came to that same conclusion from following everyone here. While my tooling is on the cheap side, (homebuilt as shown above). I realize that it will take me longer but I prefer to do it right as everyone here has stated, and assure that it lasts as long as possible. I sure would like to have a nice set up from Climax or York but I think what I have built will work well. All my welding will be E-70 wire or 7018 stick, and I may very well ask for guidance from you all here at this forum as I get involved. There is a wealth of it here and I thank you for sharing it!
I bore weld bore. I have the same problem no bore welder ,all things in time to face i use 6 inch colbolt, cat has a good listing of shims in SIS cyclinder shims nige may be better able to help with that. I agree do it once the right way
The komatsu bushings are bigger with the same pin dia. Be sure and measure one to confirm this.
You already have the stick off the machine, I suggest you lay it on its side. That way when you weld it to make the build up you will be welding horizontal not trying to work overhead on part of the bore. The common wire for that type of build-up would be ER70S-6, RayF may be able to suggest something better.
Yes,use nothing fancy. Standard Grade 6 wire is perfect. Weld radially around the bore and if I'm hand welding I leave 4 witness marks to line the bar up to.Fill them after you have set up.
Post the pin size and we can give you a list of shims of assorted thickness. Ken
Does your bucket have an adjustable bushing in it? Usually that is worn just as bad and will need to be redone to.
I also have to hand weld, I like to set up and precut then weld then cut, I weld threaded plate or nuts to work piece, center up and cut, weld then remount to work piece, I can usually get within 2-3 Thou on remount from original. In your case I would put new bushings in and center from them, then remove and cut, my set up is nothing fancy but it works well.
Another question if i may...... is there a point where the weld build up is too much? I'll try and get some pics of the boom to dipper bores tomorrow, one side will have to have almost .75" at one point, this is prior to cleanup bore and starting. Do I need to build up the bore any way or build a bushing and interference fit it in?
Personally I would say that at that thickness of build-up it's too much to think about boring oversize and bushing back to size. You may have to do some localized welding buildup in that particular area before attacking the complete bore. Without seeing the structure it's hard to make a judgment but gut feel tells me that taking a 3/4" cut out of a bore to put in a sleeve is going to take loads of strength out of the structure in that area, maybe enough to cause cracking problems in the future. I'd clean up the bore with the cutting tool as best as possible then hand-grind what the tool hadn't touched before building up with weld. Just make sure you get the bore good and clean before welding.
Building up egg shaped bores can be a bit of an art. Its hard to know how much to put in and you can get lost and lose track. Then when you cut it you have too much here and not enough there. I try and leave bearings set up and put the bar through and have a set of inside calipers set a 100 thou smaller than the finished distance from the side of the bar to the bore wall.That way you can accurately fill the bore without putting heaps to much. With the set up the only thing that really matters is that the bar is level and parallel to the next bores up the arm. Trying to set up accurately to a worn out bore is a waste of time. It doesn't matter to much where the finished bore is.It can be 50 or more thou out. If its out of sync with the next set up at best it will wear out quickly and at worst will tear itself apart.
Ray, I have had that happen to many times, then you figure one more pass to be sure, hand welding larger bores takes patients, looking forward to a bore welder.
Got started boring today on the boom today, I glad I listened to ya'll! one side bad bell shaped, the other was round for the most part, but took almost .100" to clean up. I did set my boring bar up and did my oversize boring with it horizontal, but I will most likely do as you suggest and lay it over on its side so that I don't have to deal with a bunch of overhead!
Looks good
I got to slow down my feed rate I geuss........the bore is cleaning up good, built I am having trouble with chipping my bore inserts. I went and ordered more today but I'm still on the first 2 overbores.. Reckon I better learn some patience unless these pics will show what I'm doing wrong.
Possibly your carbide is not suited. You need a tough,not hard grade. What rpm is the bar doing? HSS may be an option. A good feed rate would be somewhere between 3 and 8 thou per rev.
I'll try and keep my rate down around that, I may have been deep on my cut. I'm boring with a variable speed Milwaukee mag drill, hand feeding the rate of travel, it was really cleaning up good and I probably got greedy or in a hurry, or both.
I got back busy on my bore project, thats the way it goes when you workin on your own stuff. I did get some Cobalt steel cutter inserts so hopefully I won't break so many carbide cutters. I'm quickly learning that patience is a virtue that I have to relearn when it comes to doing this line boring!
Most cutters will chip bad out of the box, you have to sharpen them and get some better relief angles on them, both x and y or they chatter badly.
I need to post a few pictures of our wire feed bore welder. Once you've used one of them you'll never go back to doing it by hand.
Nige, only reason we do it by hand is that's all we have at the time, I have spent hours welding when I should have been machining the last cut. We must crawl, walk then run. Pics are always welcome.
well I'm getting my boring figured out, I'm glad its on my own equipment, otherwise it would be a costly learning curve. I got my bore welded up and trued up, I thought it looked pretty good see pic. then I noticed I made a BAD MISTAKE! I didn't start checking my dimensions soon enough. My purty bore is too large already! by .09"......... so much so that I am going to have to weld it up again, I am about to invest in a set of bore gauges just as soon as I get done here. I know I made a rookie mistake!
The weld has cleaned up nicely. I usually cut to size with quality inside calipres. Failing that you could try an inside mike then adjusting the tool with a dial gauge.
Can a guy take the bar size + distance from bar to hole x 2 = and get a good measurement?
I'm proud of the way it cleaned up too Ray! I just wished that I had checked myself sooner! could have saved myself some time..... I'm still a little unsure how to set up a dial indicator off of the boring bar, I did allow for using a through the bar bore indicator when I built the boring bar. I found my mistake by measuring off the bar Doug, taking the backside dimension to the tip of the bore bit, subtract .99" because the bar measures 1.99" then multiply by 2. The bushing I have to install measures 4.760" and dumb me didn't check it soon enough,... when I did, it was at 4.84" A rookie mistake I know. Since I'm beating myself up anyway, I have a question for Ray or Nige or anyone, should I be shooting for about 4.765" on the finiished bore size? for a press fit? bear in mind that I have a 30 ton press to pull in with. And only a freezer to chill the bearings.
4.755 would be good. I took some inside calipers and brazed some of my kids Bb gun ammo on the tips to make them a lot easier to measure inside the bore.
Yes ,4.755 would be good. If you don't have a manufacturers spec you can measure the ID of the bearing and compare it to the pin size. Most pin to bearing clearances are around 8 to 10 thou fitted clearance. If you put 5 thou crush on the bore the fitted ID of the bearing will come down about the same.
bvfdfire, great work. thanks for showing this, I never considered this was even possible with rather inexpensive, average tools.
bout finished up my boring project, just had a few setbacks; deer season, holidays and a heart attack. i am still kicking and bound and determined to get this finished.
I have found that cobolt cutter work good to do the first clean up pass. your bar looks like an american tool set up talk to them they helped me in the beginning.i have a dixon welding from PA. it works good I like the mannual feed. the cutters i got on ebay AND cmt.
If anyone wants to look at TJ Dixon's website here is a link. http://jtdweldingservice.com/cutting_tools__accessories
i have brought my measuring dies from dixon, they are good people. but i built the rest of my boring bar set up myself. the bar is even set up to use round by square sleeves so that i can change them out as needed. i dont have anywhere near what a setup would cost invested; including my magdrill which i found at a pawn shop.
I know this has been a long drawn out affair, but I can finally see the light at the end of the tunnel! finally finished the dipper up today, only have 2 bores left to cut on the boom; hope to get them done tomorrow. No build up needed, only about .125 to cut out. I couldn't have gotten this far without everyone here's help. Even made a few innovations of my own, had to build a couple of line up bushings from hardwood on my lathe.
Looks like a quality job to me... Well done...
A heart attack? looks like you are still kicking
last bit of boring! not a lot to come out; did have to install new rub shims first though!
You are getting into it. Did you need a bearing support in between or did it cut ok?
its cutting ok as long as i keep my cutting depth to a minimum. the bar is a 2" so i don't seem to have a lot of chatter. i also built a new bearing mount which allows my mag drill to set up at the same plane as the shaft. i already see that if i start to do much more , i will be acquiring a different drive system..... all in all though it turns out some nice bores. never could have done it without the help of some of you here at this site!
I finally made my last bore on this machine today! gota cut out a few shim washers and this puppy is going back together! had to burn some rods with my new Texas pride hood that I got for my birthday!