7/8 shank boring bars (nearly) non existent??

[hvnlymachining]

Implmex,

I have considered that method, I actually had a line borer lined up for this job, but apparently the mines pay better and they can't get to it now.

Back in my lap, so now It's on the radial, with less time to get tooled up.

If the head change doesn't work, home brew line boring may be next.

Thanks for your input!

 

[Limy Sami]

YTo the OP - What's the taper in the machine and what's the dia you're boring?

 

[hvnlymachining]

Limy Sami,

The machine spindle is 5 MT, the bore is a little over 4" in the narrow, it's egg shaped, it'll have to go out to 5" to 5-1/4" to be true again. Then sleeved or welded up, and bushing installed.

 

[gregormarwick]

You sure they're 7/8"?

Wohlhaupter are 22mm

 

[implmex]

Hi again hvnlymachining:
You can already improve things tremendously by just using one bushing at the outboard end.
It won't be great but it'll be better than it is now.
Even a mild steel spider welded up out of flat bar with a Delrin bushing knocked into it will help you a lot.
If you have some big diameter pipe kicking around you can make an end cap spider out of that...just cut cutouts around the periphery with a gas axe so the aligning cone and the chips can come out, put a cage to hold the bushing in the other end, line it up, tack it on, pull the cone, and go to town.

Of course, if you do that, you can't use universal joints...you have to rigidly tie the bar to the radial drill spindle.
It's more of a pain to align everything, but once you have it you can bore away.

Obviously you have to turn an accurate # 5 Morse taper on one end of the bar, and put in a cross hole and a setscrew hole for the cartridge
Make the outboard aligning cone shallow and tack it onto a mild steel flat bar , so you can pull it sideways out of the cutouts in the cap and so you can tack it in place with accessible tacks before you tack on the cap.

So you mount the bar in the fucked up bore with the two quick and dirty turned cones... the outboard one is tacked on the flat bar which is then tacked on the workpiece...the inner one can just be tacked directly to the edge of the hole so you don't have to build anything elaborate to hold the cones in place.
Mount the outboard cap, break the outboard cone tacks and pull the outboard cone.
Set up the drum on the radial drill with the bar still in place suspended between the outboard cap and the inboard cone.
Get everything lined up.
Knock off the inboard cone, connect the bar to the spindle and set the cartridge.
Bore away.

So some things to build, but they're simple things and you don't have to make them pretty...just functional.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[Hobby Shop]

Here’s a manual on Vintage Machinery from ATW about boring on a radial drill.

I’ve bored a few times on a RD and it turned out better than I expected. We had some homemade tooling that looked similar to the pictures in the manual.

http://vintagemachinery.org/pubs/1004/21729.pdf

 

[Garwood]

Does the winch spool have a smooth bore inside? Is it concentric enough with the ends? If it's rough can you hone it true?

Make up a 2" or so bar with a hole to hold a lathe stick tool or boring bar or even a carbide endmill ground to cut on one side. Have the end of the bar stick past the tool by the length of the bore plus an inch. On the end of the bar fit a 1/2" wide bronze pilot. Press it on and retain it with a scotch key.

The pilot will stabilize the bar and make it dead silent.

It's not the most accurate way of doing stuff, but I've bored 2.5" 30" deep holding a few thou using this method. I just used some CR 1018 bar I had in the rem pile.

 

[implmex]

Hi Garwood:
I read your approach with interest, but in the first line you said "hone it" and then you described what sounds to me almost like line boring it as I described too.
The big difference as I see it, is that you are mounting a pilot onto the end of the bar and using it almost like a travelling steady rest on a lathe...is that correct?
If so you need to either have a pretty good bore to start with, or you need your pilot to run on a pre-bored land that is round and to size, so the pilot has a true surface to run on, and you're going to continuously deepen that land as you run the bar through, so the bar has to cut to exactly the same diameter as your pilot (plus a thou or so) or else the bar is either going to rattle or the pilot is going to seize.
Obviously in this scenario, the cutter has to be ahead of the pilot.

Do I have this right?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[hvnlymachining]

You sure they're 7/8"?

Wohlhaupter are 22mm

Yep, definitely 7/8"

 

[mattthemuppet]

Hey Jacob, I think I have a bunch of MT5 taper tooling from an HBM or similar, that might be useful. There's definitely an adjustable boring head in there, but very stout. Pretty sure it came with a TNMG bar. I'll go have a dig after my coffee and take some pics.

 

[Garwood]

Hi Garwood:
I read your approach with interest, but in the first line you said "hone it" and then you described what sounds to me almost like line boring it as I described too.
The big difference as I see it, is that you are mounting a pilot onto the end of the bar and using it almost like a travelling steady rest on a lathe...is that correct?
If so you need to either have a pretty good bore to start with, or you need your pilot to run on a pre-bored land that is round and to size, so the pilot has a true surface to run on, and you're going to continuously deepen that land as you run the bar through, so the bar has to cut to exactly the same diameter as your pilot (plus a thou or so) or else the bar is either going to rattle or the pilot is going to seize.
Obviously in this scenario, the cutter has to be ahead of the pilot.

Do I have this right?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Using a portable Sunnen hone with coarse stones you can fix a bore up enough to run the pilot on it. The bore doesn't need to be perfect to get a good result. It stabilizes and guides the cutter, but it doesn't do everything. If it's 5 thou out of round you can still get a nice, straight hole.

I get what you're saying and not disagreeing with you on line boring, but I personally hate line boring. It's a huge time suck to set up, very hard to measure and adjust the cutter.

It all depends on what gadgets you have and how much you want to flip a large part around.

 

[hvnlymachining]

Does the winch spool have a smooth bore inside? Is it concentric enough with the ends? If it's rough can you hone it true?

Make up a 2" or so bar with a hole to hold a lathe stick tool or boring bar or even a carbide endmill ground to cut on one side. Have the end of the bar stick past the tool by the length of the bore plus an inch. On the end of the bar fit a 1/2" wide bronze pilot. Press it on and retain it with a scotch key.

The pilot will stabilize the bar and make it dead silent.

It's not the most accurate way of doing stuff, but I've bored 2.5" 30" deep holding a few thou using this method. I just used some CR 1018 bar I had in the rem pile.

I like this idea, unfortunately no... There is a void between the journals on either side, both of which are damaged badly. But I'll definitely keep this one in mind for future use!

 

[hvnlymachining]

Here’s a manual on Vintage Machinery from ATW about boring on a radial drill.

I’ve bored a few times on a RD and it turned out better than I expected. We had some homemade tooling that looked similar to the pictures in the manual.

http://vintagemachinery.org/pubs/1004/21729.pdf

Thanks for sharing, I hadn't thought of looking at VM. Those tools seem to echo what many here are describing in one form or another. I do like those designs for applications where tolerance is more critical. In this application tolerance is pretty open since I can make the repair bushing fit the the bore. But if I build some bushings they could make this job easier I think.

Another option, thanks!

 

[mattthemuppet]

Woohoo, I think I found something(s) that might help. The tool on the far right is 1.5" diameter by just under 4.5" long and takes a 1/2" round bit. There's a similar straight shank 1.5" bar also for 1/2" round bits, that's 6.5" from flat to tip. That also fits in the 1.5" mt5 holder. $10 a piece for the tapered stuff, $5 a piece for the straight stuff.
Foot for scale

 

[implmex]

Hi Garwood:
Thanks for responding...gotcha...that now makes sense to me.

On another note...this is not the sort of stuff I normally do, so I have very little experience working at this scale and the practical problems of just flipping a part over for example, are completely foreign to me.
Your insight and those of others who do this for a living often surprises me but once it's explained...yeah I get it.
I figured line boring was the obvious way forward, and I assumed all would agree with the basic premise.
I appreciate the lesson about how it's just not that easy to do when the part weighs several tons and you have to work on it from both ends.

I do have to say I'm glad it's guys like you and not me that has to jack your parts around with a bridge crane...I'd rather lose a few when I drop them on the floor and can't find them again.
So thanks for the education...I learned something new today.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[hvnlymachining]

Matthemuppet,

PM incoming.
How much can you stuff in a box?

 

[mattthemuppet]

Matthemuppet,

PM incoming.
How much can you stuff in a box?

quite a lot. The 70lb weight limit is usually the problem

 

[gbent]

With that size of bore, it would be easy to make an align boring bar. Start with a piece of 2" TGP and machine a mt5, complete with slot for draw key. Make a collar to hold your tool bit. The collar can be simple with a 1/2 x 1/2 slot for a tool bit, and then tack weld a plate over the slot for a square hole. You can grind a 45 degree angle on the back of the tool bit and use a push screw at 90 degrees to extend the tool bit. Use a flange bearing to guide the bottom end of the bar. Make a spacer to raise the flange bearing enough to give you the necessary travel in the bar. You can clamp the spacer down after the align bar is in the spindle.

The boring collar is where the DeVlieg cartridges fail. The simple cartridges require access to the back end to loosen and tighten the lock screw. Erickson used the same principal and somewhat interchangeable, but adjust with a front nut. However, I don't recall ever seeing a 90 degree mount Erickson, they are all angle mount (more work to machine). The DeVlieg cartridges have graduated dials available for both angle and straight mounting.

I will leave the various lengths for you to figure, but I would expect 16" of travel on a RAD with a #5 mt spindle. Should be enough for 12" of cut.

 

[hvnlymachining]

gbent,

Thanks for the idea, sounds like another one to try, if not on this job, then on another. I'm sure either way it won't go to waste!

My RAD( Fosdick) has 22" of travel on the spindle.

 

[Greg Menke]

Maybe skip the fancy boring head and set up a small el-cheapo one that will fit down the bore with cutter projecting horizontally? If the radial's spindle is too large for the bore then fit up with suitable length of the largest reasonable round bar and support it with a flange bearing as suggested, blocked up enough for the head to be drawn out of the work for adjustment/cutter change.