got plans for a thumb to put on my backhoe but....any easy way to ream out steel bushings a couple of thousands? I've got 2- 2" long X 1-1/4" chunks of ROM pipe that measure 1.246" inside diameter. I'd like to slide a cold-rolled rod that measures 1.248" OD thru them and have it a loose fit for easy removal of the thumb. . so I'm thinking I gotta get up to 1.250+ on the bushings. they don't have to perfect but not sloppy. short of buying a $50 adjustable reamer, is there another way to 'stretch' these bushings? i've also got a couple 2" bushing that need stretching, too, for the same project. thanx in advance for any tips.
reaming bushings
- Thread starter wowbw7
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Get a long thick bolt. Cut off the head, use a sawzall to slit it 1/2 way down the length. Put some sandpaper in the slit and wrap it (grit out), until it just barely doesn't fit in the bushing. Chuck it in a drill and go after it. Fairly slow and definite in/out motion. You will cut 0.001 every 15-120 seconds depending on the materials, grit, pressure, rpms.
Obviously, start slow and measure often. It's much easier to cut metal out than to glue back in all those little chunks.
jb
Obviously, start slow and measure often. It's much easier to cut metal out than to glue back in all those little chunks.
jb
CurlyDave
Elite Member
Of course, an alternative is to take your pin to a shop with a centerless grinder and have it sized down to be a slip fit.
jmc
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I think you may want more clearance than a couple of thousandths, especially if you are going to weld it in and get some distortion, and especially especially if you are going to weld a pair of them in and they won't be perfectly coaxial. Some guys on this board use 1/64" clearance on a 1" shaft. Find a hobbiest or vocational school with a lathe and have them bore it. Good luck.
John
John
Yeah, but he would have to take the dipper stick off the hoe, that's heavy and messy. The expense of that at the machine shop is probably going to be well over $100 as it's a PITA to fixture up a dipper stick. An old bolt and some sandpaper will get the job done faster than he could get the dipper off the hoe!
jb
thanx for he help, fellas. the bushings are on my bench, not welded up yet. but i live 60 miles from the nearest machine shop/school so that is a very last resort. (one of the disadvantages of living out in the dingles) the 'bolt/slot/emery cloth trick' sounds like the only option open right now unless somebody else chimes in with a better idea.
mattman
Gold Member
You can use a brake cylinder hone.
Hooked_on_HP
Veteran Member
I use an air diegrinder with a long 1/4 cotterpin. Spread the cotterpin enough to get the sandpaper between it then squeeze it back together ad put it in the chuck.
ampsucker
Platinum Member
what is ROM pipe? i guess from your post you are using that as the actual bushing material?
depending on the hardness, sandpaper might work but will be tough to get a perfectly even ID.
i guess it wouldn't matter too much as the thumb doesn't really pivot or rotate very much. as along as the material is hard enough to work as a bushing and won't deform, i like the emery cloth or sand paper idea for the small amount of material you want to remove.
you might also try taking material off the rod you want to use. might be easier with a belt sander or such.
amp
depending on the hardness, sandpaper might work but will be tough to get a perfectly even ID.
i guess it wouldn't matter too much as the thumb doesn't really pivot or rotate very much. as along as the material is hard enough to work as a bushing and won't deform, i like the emery cloth or sand paper idea for the small amount of material you want to remove.
you might also try taking material off the rod you want to use. might be easier with a belt sander or such.
amp
I think he had a typo. Should have been DOM for Drawn over Mandrill. Thick wall tube, basically.
I've tried the brake hone. All it did was wear a good hone down to nothing quick. I've done about a dozen bushings and the bolt sand paper route works pretty good. I use long board paper for a straight line sander. 80 to 320 grit. It will wear the paper down fast.
I've tried the brake hone. All it did was wear a good hone down to nothing quick. I've done about a dozen bushings and the bolt sand paper route works pretty good. I use long board paper for a straight line sander. 80 to 320 grit. It will wear the paper down fast.
-yup, you' right. it is DOM tubing. don't know the hardness but 1/4 inch thick walls should be good for what i need
-i've got a die grinder with a couple carbide bits. maybe i'll try to rough out some with that then smooth with the sandpaper trick.
-i really don't want to remove any material from the outside of the shaft as it has to go thru 2 bushings in the boom which are already a little worn.
i''ll try to get out to the shop tomorrow and try the grinder. not really looking forward to it tho...unheated shop and it's 6 degrees right now (10 PM)
thanx for all the suggestions
-i've got a die grinder with a couple carbide bits. maybe i'll try to rough out some with that then smooth with the sandpaper trick.
-i really don't want to remove any material from the outside of the shaft as it has to go thru 2 bushings in the boom which are already a little worn.
i''ll try to get out to the shop tomorrow and try the grinder. not really looking forward to it tho...unheated shop and it's 6 degrees right now (10 PM)
thanx for all the suggestions
This place has decent prices for Reamers.
Enco - Guaranteed Lowest Prices on Machinery, Measuring Tools, Cutting Tools and Shop Supplies
Enco - Guaranteed Lowest Prices on Machinery, Measuring Tools, Cutting Tools and Shop Supplies
Oldmax
Silver Member
Use a adjustable reamer .
J_J
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Can you find a grade 8 bolt that size? I found out that when looking for pins for 1 in DOM, that 1 in steel rod would not fit, so I had to ream out about 6 or 8 bushings. I then learned that you can get pin stock that is a couple thousands less than the bushing size, and that is what I am using now. A grade 5 or 8 bolt will sometimes measures less than the listed size.
