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Thread: Filling in Holes in Iron
06-26-2009, 09:27 AM #1
Filling in Holes in Iron
Some of you may be following my thread on the Antique Machinery forum on building a working steam driven hand sheet rolling mill. (Yes I am crazy, but thats besides the point) Even crazier is that I intend to transmit power from the steam engine to the mill stand using hemp rope, a technology that was once widely used to drive rolling mills but has completely and utterly disappeared from the face of the Earth.
I recently acquired the six groove rope pulley which will become the driven pulley. For the driving pulley I plan to modify the old generator rotor on the engine's crankshaft. This rotor is 51" diameter and 8" across the face. I plan to cut the rope grooves right into the face of the rotor. However ther rotor has (64) 13/16" holes drilled into it, both line of holes right where two of the rope grooves will go.
I'll need to fill in these holes since the holes would rapidly wear away the hemp rope if left in place. What would be the best way to fill these holes? I'll have to use a material that is not any harder than iron and that would stay put.
One idea I had was to fill each hole with babbitt. Tap the rear of the hole, put a plug in place then fill the hole solid. But would the babbitt stick? The wheel is quite a heat sink and I envision failure due to such a small amount of babbitt immediately cooling upon hitting the iron.
What about iron plugs? How could I hold the plugs in place? Press fit? Loctite? I suppose I would have to ream out each hole and then have the plugs made to size. Mcmaster has 1" dia. iron rod available, I suppose that could be turned down to 13/16 and then each plug loctited in place with the non removable loctite.
So I'm asking those of you with more experience than me, what would you do?
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06-26-2009, 09:35 AM #2
How about tapping for a tapered pipe plug ?
Can this fit under Mad's radial drill ?
And after tapping, plug using standard cast iron
pipe plugs dipped in (how did the old timers get
a rust joint) acid and iron fillings ?
Then using and angle grinder (by hand)
snag off the protuding square (wrench
flats on the pipe plug) down flush to
06-26-2009, 09:37 AM #3
I appreciate your fascinating threads and great photos.
As for the rotor, I'd think about reaming the holes with a taper and pounding in some tapered pins.
If you want you can run a little weld around the hole afterwards or added resistance to the vibration frequent loading/unloading that I am sure this part will see.
06-26-2009, 09:42 AM #4
06-26-2009, 09:48 AM #5
Instead of cutting groves, could you have some sort of channel bent into the proper diameter circles and install them like "tires"?
06-26-2009, 09:58 AM #6
I have no experience at all with what you are doing.
Cut the grooves, spin a wire bottle brush in the holes to clean out loose scale, tamp a wad of newspaper in the bottom of the hole, and slightly overfill fill with home made JB weld made from two part epoxy and steel or iron filings. After setting, smooth with a round file to the contour of the groove.
Auto body Bondo with iron or steel filings filler might work. That is a polyester resin base.
Making iron plugs and loctite would work.
I did think of making plugs slightly oversize, cooling in dry ice and driving in, but the expansion along the lines might split off the two sides. Then cut the grooves.
Threading the holes, screwing in bolts that were grooved to snap off when hit with a hammer. Permanent loctite on the threads.
Last edited by paul39; 06-26-2009 at 10:01 AM. Reason: add comment
06-26-2009, 10:16 AM #7
How about "ronTite" cast iron plugs? Size?
06-26-2009, 10:59 AM #8
The crankshaft is installed in the engine and it would be easier to bring a radial drill to the wheel than take it back out, after it took me months of work to get it where its at.
With the cost of the epoxy putties being what it is, such a repair would probably be the high cost solution. Each hole would probably consume a tube of JB Weld, 13/16" dia. x 3" deep. However bondo may be a possibility. I suppose I could mix iron filings into the can to achieve a better color and maybe add a bit of wear resistance.
Hemp rope wears best in cast iron, and in grooves of a certain profile. Its hard to achieve by other means. I plan to machine the grooves using the same techniques used by steel mill roll shops turning grooves in mill rolls. Ever see how a block lathe works? My setup will be a combination of block lathe and pit lathe.
Tapered pins could work, however where would I get 64 tapered cast iron pins? Anyone care to quote making them for me?
06-26-2009, 11:44 AM #9
Hi. Isn't 13/16 a tap drill size fore something ? dont have the chart at hand then tap the hole 2 1/2 dp. thread the 1 " iron rod to fit ,install w/loctite and cut off . use green.
06-26-2009, 11:51 AM #10
Upon further thought (I have been accused of thinking too much) I wonder if you need to fill the holes.
After you have cut the grooves, using a die grinder and a tapered stone just a little smaller than the hole, round the edge of each hole swinging the grinder in the direction of the groove in both directions.
You have so much area of solid in comparison to the holes, and also 4 solid grooves, the stretch and creep would be minimal. A nice smooth radius on the holes would not cut the fibers.
I wonder if one of the mechanical engineers on this site could think about this, and calculate total loading of the 6 ropes, then figure load on one, and if the holes would make much difference.
You could do a test by making one groove, do the grinding and using whatever motor you can lay your hands on, splice a rope and pull it as tight as possible, run it for several hours and see if you are getting any cutting or shedding of fibers.
I think I see above that the rotor is mounted so that should not be too hard to do.
If it is still loose, you can make bearings by bolting two 6 X 6 or 8 X 8 timbers together and drilling the right size hole for the shaft.
Shine up the shaft with sandpaper, finishing up with 600 or 800 grit lubed with kerosene or diesel, clean off the grit, grease everything with axle grease, mount on timber cribbing and go.
Quote "With the cost of the epoxy putties being what it is, such a repair would probably be the high cost solution. Each hole would probably consume a tube of JB Weld, 13/16" dia. x 3" deep. However bondo may be a possibility. I suppose I could mix iron filings into the can to achieve a better color and maybe add a bit of wear resistance."
I was thinking liquid epoxy from boat stores with added iron filings. About $32 a gallon several years ago. Epoxy grabs metal better than Bondo or polyester boat resin. It would take 4 - 5 tubes of JB Weld at $5 a tube per hole.
I'm jealous that you have a steam engine in your garage.
Last edited by paul39; 06-26-2009 at 12:00 PM. Reason: add comment
06-26-2009, 11:59 AM #11
Figure out how deep the groove be when cut. Cut wood dowels to fill about half the void depth, when fill with Devcon Plastic Steel. Maybe drill some small shallow holes tangent to the 13/16 hole to act as pins when filled with Devon. This is real hard stuff when cured..
06-26-2009, 12:05 PM #12
"But would the babbitt stick?"
Maybe the babbitt doesn't have to stick in the "soldered" sense. Plug the hole with babbit and peen it until it expands radially to fill the hole tightly.
Maybe plumber's lead, which is cheaper, would work for this.
How hard would it be to experiment with this method on a single hole ?
06-26-2009, 12:19 PM #13
Well, there's always a mag base drill.
I don't understand the usage of a tapered (non threaded) pin.
Yes there will be vibration (some), there will be stresses and
relaxtion of that stress. Any hint of looseness would immediately
pop loose a tapered pin. A straight press fit pin would be better
from that standpoint.
Adding a bit of weld to cast iron is problematic in it will (under
cooling stress, or operating vibration) crack. Also, pretty much
any heat is going to eliminate (or reduce) any shrink fit.
What I would really like to see, is those tapered pipe plugs installed
from the inside out, but I figured that is asking for too much.
One little hitch here, the tapered pipe plugs, some of the larger sizes
are cored on the inside, which negates their usage in this application.
Straight pins (in a reamed hole) are do-able. 64 straight pins I see.
Would reaming out to 7/8 (or less if they all clean up)
be do-able ?
Freezing in L.N. might make things easier.
06-26-2009, 01:26 PM #14
a quart of epoxy resin and hardener
and a bucket of cast iron chip from your local brake lathe
magnet winnow out the good cast chip, and mix with the epoxy resin
and fill the holes.
very cheap, and hard as it needs to be
i use fiberglass resin the polyester stuff, but epoxy resin will stand more heat.
composite cast? where have i heard of that used before?
btw,, if you are worried about bonding, just tap a few treads in each hole, so that the composite cast material has something to "tooth" into.
06-27-2009, 09:48 AM #15
What's a block lathe? What's a pit lathe?
06-27-2009, 10:33 AM #16
06-27-2009, 10:41 AM #17
I think I'd hand tap the 13/16" holes with a 7/8-14 tap. Drill a bit oversize if you must, to clean out the crud and make the hand tapping easier!
You could then fill with a threaded cast iron plug and loctite or epoxy.
You could fill with an epoxy/cast iron chips mix.
You could pour the babbitt and it would flow into the threads.
06-27-2009, 11:51 AM #18
don't make it so complicated, just use iron plugs. turn iron plugs for a light press fit. if the holes aren't consistent, ream by machine or hand first.
they used to used to do the same to plug holes in cast iron boiler parts, and legend has it, they would urinate on the plug first - supposedly the slight acid nature of it would help.
06-27-2009, 12:02 PM #19
Filling holes in iron
I would not use Loctite in this situation due to heat breaking down the Loctite & turning it back to a liquid state which would cause the plugs to fall out. Tapping would be time consuming. I would clean up all the holes to the same size, then turn soft iron plugs for a press fit
06-27-2009, 12:57 PM #20
I'd vote NO for Babbitt
Even if you chased a thread or two in the hole to allow the babbitt some tooth, it would not wear at the same rate as the iron so you'd get little depressions at each hole after a while.
The goal should be to provide a homogeneous material once the groves are created. As suggested, I'd go with straight (not tapered) holes with a light press fit rod or threaded holes with screwed-in iron plug. You don't want a hard press or shrink fit. With that many holes, you risk splitting the sheave.