Help w;th designing a hand-held reamer for a precision fit hole.

[PackardV8]

Yes, the following is not best science, but that train is out of sight long ago.

The workpiece is a rebuilt cast iron long block engine in which a .5625" diameter through hole 1.5" deep and 8" down inside the block must be reamed to .690" to receive a bronze bushing.

Since the engine is assembled and unwieldy to get back on a mill table, I'm hoping to do the operation with a piloted reamer in a hand held drill motor.

First thought, Make an arbor a precision fit in the .5625" hole, with a .500" or even .375" shank. Use the existing hole as the pilot, install the cutter above the pilot. Is there such tooling as a mountable end cutter .690" OD? If so, what is the nomenclature?

Second thought, More expensive; have a custom .690" extended shank reamer made with a solid .5625" pilot. Who would you go to for that request?

Third thought, Buy an extended length .690" chucking reamer and have the end ground to .5625" as a pilot. The quick search I did found some carbide tools for $250. Since this is a one-time operation, who would have HSS?

What other tools and operations would accomplish this?

Thanks in advance.

jack vines

 

[dian]

a 17.5 mm reamer might do the job just fine. (i havent seen a reamer that doesnt make an oversized hole.) assuming there is a reason to use that exact size bushing.

 

[stephen thomas]

I'm having trouble imagining that as a reaming job. .1275" or just over 1/16" per side.

If hole location is critical, i have made up and used a piloted HSS bit boring bar set undersized, and used same. It had a sleeve follower that was on-size to the everging bore as the cutter advanced. Then ream for finish and to straighten.

If instead, there is room and features to add bushings on each side of the bar, it can be done as line boring under power. For instance, either side can be as simple as a bolted on and indicated piece of aluminumwith a bore the same size as the bar. Refinements can include one of the plates having a hat insert so the bar can be removed and the work checked.

I've done most of the above at one time or another.
Also routinely grind pilots on drills, or the occasional reamer, as useful & modify lip geometry as necessary.
Generally it was for rebuilding machines/equipment, not automotive where the risks might be higher?

smt

 

[DDoug]

I thought I have seen adjustable line reamers, with a square end for hand use.
Old time automotive use.

Heck I think I may have an old set of them, bought at a flea market years ago.

 

[Bobw]

I just checked.. All the reamers I have in the .688 range have a .561 shank..

Sharpen the upper end of the cutting flutes, and pull it through..

Probably open up the flutes a lot, gonna be a lot of chips... Maybe
even neck it a little ahead of your new cutting edges so that you
can sharpen in past the .561 diameter..

By sharpen, I mean put on the old man eyeballs, and grab a tiny cutoff disc
on a dremel tool.

I'd probably want to ream a bit smaller. .688 or .6885 so that you don't
go oversize. Maybe even a straight 11/16.

 

[PackardV8]

I thought I have seen adjustable line reamers, with a square end for hand use. Old time automotive use.

Yes and I have a set also. They're mostly used for cleaning pressed-in bushings to size. They don't remove an eighth-inch of cast iron.

Of course one responder doesn't think it is a reamer job either. That's why my first thought was a cutter which may not exist.

jack vines

 

[Conrad Hoffman]

Could you make a DIY 1/2 round drill?

 

[DDoug]

Yes and I have a set also. They're mostly used for cleaning pressed-in bushings to size. They don't remove an eighth-inch of cast iron.

Of course one responder doesn't think it is a reamer job either. That's why my first thought was a cutter which may not exist.

jack vines

I'm sorry.

I'm sorry I took the time to read your thread, compose a possible solution to HELP YOU.

On the ignore list you go.

 

[Scottl]

Question: Instead of a piloted reamer could you use a guide block instead? If there is room, you could make a guide block with different size holes so you can enlarge it in stages instead of one deep cut.

That way, you could first use a series of drills to get to rough size and then use an adjustable hand reamer to finish.

I once made something similar out of aluminum to drill and tap an engine for helicoils while it was still in the vehicle.

 

[strokersix]

Is it possible a piloted counterbore intended for socket head cap screws might work for you? Make a 0.5625 pilot for it.

edit: counterbore for M10 looks about right on the OD. Add a sleeve to the pilot if it can't be replaced.

 

[PackardV8]

Thanks for all the great suggestions. I now have a plethora of possibilities I hadn't considered.

I believe an 11/16" piloted counterbore might be the off-the-shelf answer.

To Digger Doug, my apologies. Thanks for making a suggestion and I'm sorry for having given offense.

jack vines