Limits of hand-reaming

Rockmonton · May 21, 2021

I have two 30mm holes that I need to bore out to 32mm and stay mostly-aligned. I'm converting from a plain bush to a bearing on both ends. I have a 2201 in my surplus pile and the other will be 6201, that should allow a decent amount of misalignment.

Unfortunately none of my equipment is big enough to set up and bore properly.

However, I do have a set of adjustable hand reamers available in the proper size. I've used them before to take off up to about 1 thou, but never tried to go out to get 2mm of clearance.

Would I be crazy to try it in cast iron? What are the limits for reaming in a reasonable amount of time?

Limy Sami · May 21, 2021

Out of your tree

Just my 2 cents YMMV

HuFlungDung · May 21, 2021

Hand reaming is a real biatch if you don't have a pilot on the reamer, and a hole to guide the pilot with. This is generally a second hole a few inches from the first hole. Maybe you can set your parts up inline to accomplish this? With a pilot to steady the reamer, you can make decent progress, but you're still limited to the strength you have to turn the reamer. Just 40 passes and you're done

JS · May 21, 2021

[

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DDoug · May 21, 2021

Rockmonton said:
I have two 30mm holes that I need to bore out to 32mm and stay mostly-aligned. I'm converting from a plain bush to a bearing on both ends. I have a 2201 in my surplus pile and the other will be 6201, that should allow a decent amount of misalignment.

Unfortunately none of my equipment is big enough to set up and bore properly.

However, I do have a set of adjustable hand reamers available in the proper size. I've used them before to take off up to about 1 thou, but never tried to go out to get 2mm of clearance.

Would I be crazy to try it in cast iron? What are the limits for reaming in a reasonable amount of time?

So go GET the right equipment....mainly a portable line bore kit.

sfriedberg · May 21, 2021

Just to be 19th Century about it, enlarging the bore in a casting was occasionally handled by human-powered boring bars, particularly when the work was too big to swing on any of the shop's lathes. The bar would be turned to a nice fit in the existing bore, and the tool would be extended to take essentially the entire cut. So full depth of cut, but very fine feed. Feed was usually provided by gravity, and drive by the shop apprentice. Works OK in grey case iron, not nearly so well in steel.

In your case, you could bore to your preferred few thousandths under the target ID, then ream.

Rockmonton · May 22, 2021

But that costs money and I'm just a broke-a$$ hobbyist who mostly works on farm equipment for friends and family. The real answer is I need a proper sized mill. Machine shop in town quoted me $1200 which is insane (live in a small mining town). I might still just drill to 1.25" on the drill press and ream to size, but mounting the casting will be difficult to get relatively straight... I'll let you know how it goes.

Limy Sami · May 22, 2021

Whatever

Madis Reivik · May 22, 2021

Rockmonton said:
I have two 30mm holes that I need to bore out to 32mm and stay mostly-aligned. I'm converting from a plain bush to a bearing on both ends. I have a 2201 in my surplus pile and the other will be 6201, that should allow a decent amount of misalignment.

Unfortunately none of my equipment is big enough to set up and bore properly.

However, I do have a set of adjustable hand reamers available in the proper size. I've used them before to take off up to about 1 thou, but never tried to go out to get 2mm of clearance.

Would I be crazy to try it in cast iron? What are the limits for reaming in a reasonable amount of time?

Its a big reamer and you can remove 0.1-0.3 with one pass. So, about 10 operations per hole.
Nothing to be afraid of, lube well and be patient.

crossthread · May 22, 2021

Of course you can do this. Would it be the way to go for production? Heck no, but as you said, you are just trying to help a brother out here. If I had to choose a material to attempt this it would be cast iron. I have "line" bored quite a few messed up journals with home made reamers. My favorite is just a round bar that fits the old journal with a round HSS in a cross drilled hole in the bar. Kind of like an old fashioned boring bar with the bit way back from the end. Cross drill for the bit and another perpendicular threaded hole for a set screw. Adjust the bit out a few thousandths and crank away. If the bar gets sloppy you might even need to turn another one to fit the new bore size but yes it can be done. I used to do this quite often with dirt bike swing arms where the needle bearings had locked up due to crud and poor maintenance and needed to be reamed for an oversize bearing. Fixturing a swing arm is a bitch and it was much easier to hand ream. They are aluminum so the job goes surprisingly fast but the same principle would apply to cast iron, just slower.

doug8cat · May 22, 2021

Not to throw more variables in here, but you could go with an adjustable reamer if your worried about trying to remove too much material at one go. Start with removing a mil (2mm overall) and work up to final size, this will also allow the you to check the bore size as work up and not over shoot.
Just FYI when I am reaming (whether it is 3/4" Dia. bore or 2.75 Dia, do a lot of big big bores.) I will ream say 0.125 DOC then check the bore for size. Why you ask, well we basically it comes down to the tooling, we have a lot of older "well used" reams. It as saved mey ass many times, do the same thing when creating the bore that will be reamed to size. You may use the proper drill size, but for some reason it may drill larger than expected, so take a second to drill in ~1/8" check size, all is good carry on. When your working on a 1.5 ton casting that has taken a week to machine the last you need is to screw up the last 2 or 3 ops.

lionelt · May 22, 2021

When I did swinging arm on Pather 120 back in the day used an adjustable reamer with a pilot on the end with brass cones that fitted in the opposite end to keep reamer in line. The bushes were from a truck possibly a Foden, or AMC? bushes were undersize internally and needed reaming. Had similar adjustable reamers for car suspension bushes all had pilots and cones.

Clive603 · May 22, 2021

In a similar situation I converted a hole saw into a crude "line borer thingy" by fitting a round guide stub into the centre of the hole saw. Nice running fit and maybe an inch sticking out. Put a couple of through holes in it at the tooth line to give the cast iron dust somewhere to go. Also added some oil grooves to reduce the chance of jamming. Unconvinced that the dust escape holes and oil grooves worked as per plan but spinning it with an electric drill, Mr Black & Deckers cheapo two speed, got the job done.

These days I'd use my big ass Makita 18 V battery drill and run a bit slower.

Finished off with the one and only adjustable reamer I had at the time which just went small enough.

Messy job. Looked like a coal miner by the time I was done. Did I say messy, really messy.

Plan A was to fit bushes. In the event I just ran a shaft direct in the hole after turning the ends down. So it was a pretty decent bore.

Not the first time a bit of creativity and a hole saw won the get out of jail stakes. Won't be the last time either. Reckon my collection spends more time on "creative" uses than doing what they were made for.

Clive

Nmbmxer · May 22, 2021

I’d make a line boring bar. Make one end pilot off the existing 30mm hole and the other a running clearance on the newly cut 32mm hole. If you make it long enough to pass thru both holes you can line bore it in one go. Then finish with the reamer.

JST · May 22, 2021

I have several adjustable reamers (yeah, I know....) which have extensions on them for line boring. A couple have the cones on them for alignment in different sized holes.

Yes, I have used them, and they do work fine.

Will the job be a bit of a pain? Probably.... but you are just doing one part. There is likely a way to make an alignment device to ride the end of the reamer.

Lotta first world thinking here. But that's not the only way to get it done.

GregSY · May 22, 2021

When I was kid, several of the fathers in the neighborhood decided they would erect basketball goals at their houses for the kids.

None of them wanted to buy pre-made basketball goals (which I understand full well), and they knew of a pile of 4" Sch 40 steel pipe they could buy at scrap prices.

They were all too economically minded to seek out someone with a bandsaw, or cutting torch. Instead, they hacksawed, at 45 degree angles, the 4" Sch 40 pipe so as to create the necessary bend needed. Then, they hacksawed the other ends to length and made some 2" channel iron supports for the backstop. They also hacksawed those.

This incident - which lasted several days - sticks in my mind as a model example of how I've learned from my father (and the fathers of others). I recall how they did something, then I use that as an example of what not to do, no matter what. This is why I generally buy nuts and bolts and don't try to make my own screwdrivers.

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Limits of hand-reaming

Rockmonton

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Limy Sami

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HuFlungDung

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JS

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DDoug

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sfriedberg

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Rockmonton

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Limy Sami

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Madis Reivik

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crossthread

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doug8cat

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lionelt

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Clive603

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Nmbmxer

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JST

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GregSY

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