# Big Boring Machine



## JohnG (Jun 6, 2021)

My woodworking was tending toward delicate pieces. I started thinking about a change of pace: something big, structural, imposing--a pagoda perhaps. I called this a gazebo when I talked to my wife about it. We know people who have those. It sounded more practical.

The timber joinery I’m thinking about uses wooden pegs or dowels, much bigger than any I’ve used. This would require a large drill, capable of boring precise holes 1” to 2” in diameter and up to 8” deep into the sides and ends of timbers up to 8” square. This will be made mostly out of stuff I had lying around, especially pieces of old production machines I had history with.

I started this in January. Most of the time I was pretty sure it wasn’t going to work. The axial alignment needed for the long travel of the drill worried me. There is actually nothing at all practical about this project; but, despite my misgivings, here it is: so far, so good.




I started with this 4 ½” diameter heavy wall steel tube, old well casing, I think. I needed 6” off one end. My cut off saw was at this a while.


I turned the tube’s o.d. and set it up in a 4-jaw chuck and steady rest. I don’t have the ability to broach the large keyway needed for the gear rack that will move the quill, so I turned two plugs like the one on the lathe carriage. They have milled slots that will become the keyway when the plugs are pressed into counterbores in both ends of the tube.



I planed a hardwood stick about 18” long to a snug fit in the slots and used it to align the two end plugs as they were pressed into the tube. They were bolted in place, and I was ready to finish bore the quill guide.



The depth of the keyway slots is about 0.020” shy of the o.d. of the quill bore. I thought I’d get a smoother, truer bore if it was an uninterrupted cut. My ability to grind a boring tool was much improved at this point.



A little work with a hack saw blade and a file cut out the two slivers of steel left across the gear rack slots.




The quill is made from a drill drive shaft like this one off a patio door machine originally built in 1968. Sliding wood doors were built by the hundreds of thousands in those days. This was a heavy machine, built for continuous production, made just to cut the slots and holes for door rollers and locks. It ran until 1990. I rebuilt it in 1991 to install European mortise locks that were the latest thing then, and it continued working until 2000. I brought home a few components when it was scrapped.




I turned plugs for the bearing bores at either end of the tube so I could mount it between centers and turned the o.d. I set an indicator against the tailstock and budged it a thousandth or so to get the same o.d. at both ends, but there was a slight, barely detectable, bulge in the middle. The quill slid into the bore about 1/3 of the way and stopped cold. A little blue layout dye found the exact spot. I was able to feed the grinder in at that point and just skim the center portion of the quill.




The fitted quill went over to the milling machine to get a slot for the gear rack.




I milled down the rack a bit and set in into the quill with 3 cap head bolts from the back side. I worked the stiffness out by sliding it back and forth a few times by hand to burnish the machined bore with the ground quill.


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## FOMOGO (Jun 6, 2021)

Some very nice work there. Cheers, Mike


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## Martin W (Jun 7, 2021)

Excellent!
Martin


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## sdelivery (Jun 7, 2021)

Nice project....you do know that craftsman do and did this kind of work with a "brace" by hand, right?


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## Papa Charlie (Jun 7, 2021)

Excellent workmanship.


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## francist (Jun 7, 2021)

I don’t know if I’d be up for too many 2” holes with a brace but one of these might be interesting to have a few tries with…



I’m liking JohnG’s project — nicely developed and a worthy construct from mostly salvaged parts. 

-frank


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## sdelivery (Jun 7, 2021)

I like the project also.
Seems like he built a mini gun drill...well sorta


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## Illinoyance (Jun 7, 2021)

I like your lathe.  I had a 13 x 30 P&W like yours.  In spite of having been abused and badly worn it was the sweetest lathe I ever ran.  The feed stop on the cross slide and the single revolution clutch on the leadscrew made it great for threading.  Mine had a Buck & Hickman property tag and a 400 volt motor so I know it had been to England and back.  It was probably nearly worn out doing war time production.


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## JohnG (Jun 7, 2021)

I am very fond of my P&W lathe.  I know it was built in 1950 and has tags indicating it was originally used in an armory. I bought it from a high school machine shop.  Neither it nor I need to earn a living anymore, and we just have fun together.


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## JohnG (Jun 9, 2021)

The quill needs to sit on a pedestal that will put the center line of the drill about 5 ½” above the machine base. I set the housing on a surface plate and laid out 4 coplanar holes for pins to support it in the milling vise. The flycutter uses ¼” shank single point lathe tools. I bought a box of these with carbide tips from China. They need to be ground before use, but this has become my go to tool on the mill. There’s a lot of lateral cutting force, so I have a piece of heavy angle iron bolted to the mill table as a backstop.




The pedestal is 2 pieces of 1” x 6” channel iron stacked on top of each other. I had to make several cuts on the mill so they would stack machined surface on machined surface. This flat on the top piece will match the flat I just made on the underside of the quill housing. The channel iron wanted to squirm around in the vise, and the bar clamps stopped that.




The quill housing has gone over to the drill press to get holes drilled and tapped for 4 bolts and drilled for 2 locating pins.




Here’s the quill sitting on its base. I don’t think the ½” chuck that was originally mounted in it will be up to the task I have in mind. Fortunately, the end of the shaft is just the right size for the 1” x 8tpi screw mount of this 5/8” headstock chuck. I milled shallow flats on the back side for a thin wrench, set the shaft in the 4-jaw chuck truing it off the bearing, and turned the threads for a very tight fit. My biggest worry in this project was the alignment of this chuck on the drill spindle.




The pinion gear needs to go into position to drive the quill rack. I milled this slot by sinking 2 narrow slots across the housing, taking out the pillar between them with the fly cutter, and finishing it to width for the axle block. I didn’t think I could accurately locate the bottom of this to put the gear axle at the right clearance from the rack, so I cut it to what I hoped was just a little deep. Then I sunk the entry hole for the gear.




I had to buy the pinion gear. I sunk a second hole though the ¾” bar that will hold the ½” axle.




I’ve always felt awkward positioning an indicator at the 4-jaw chuck. Something gets bumped the first time the chuck turns. Something doesn’t quite reach. Something blocks the view of the dial. I learned a few moves doing this project.




After drilling, the hole for the pinion gear axle is hand reamed.





Before the handwheel hub is drilled and tapped for spokes, it gets a bevel on one side to dish the spokes for hand clearance. There’s a ½” mandrel in the bore to align it.




It did take a 0.015” shim under the axle block for the pinion gear to mesh smoothly with the rack.


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## hman (Jun 10, 2021)

JohnG said:


> I’ve always felt awkward positioning an indicator at the 4-jaw chuck. Something gets bumped the first time the chuck turns. Something doesn’t quite reach. Something blocks the view of the dial. I learned a few moves doing this project.
> 
> View attachment 368721


In one of Joe Pie's videos, he shows a neat solution to this problem.  Find 4 pieces of flat stock a couple of inches long.  Hold them on the outside faces of your rectangular part with a rubber band.  Touch a DTI to the inside faces of the four flats.


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## JohnG (Jun 13, 2021)

The casting for the machine base was once part of a production clamp used to assemble wood window sash. I grabbed a pair of these on their way to the dumpster thinking they would someday be the perfect base for something: straight, stiff, stable, and right at waist height.
	

		
			
		

		
	




I’ve laid out the location for 4 holes to be drilled and tapped to anchor the quill to the base.



I was really pleased with how solid the quill felt after it was bolted to the machine base. I set an indicator on it to tram the base and was surprised when it trammed true on the first try. I did go to some lengths with this in mind, but I’d have to say I got lucky here.




The motor is 1 ½ hp, 3500 rpm, 3 phase. It weighs a ton, so it can’t just hang off the back end of the quill. It will ride on a trolley made out of a piece of ½” aluminum plate with some small ball bearings as wheels. The plate has a couple of grooves cut in it that register on the motor’s cooling fins, and the bearings are placed to have clearance under the motor.

I pulled the motor apart to reverse the end housings so the electrical box would be on the back side away from the operator. Inside, the front bearing, with a zerk fitting, was encased in a ball of grease. The back bearing, with just an access cover, looked like it hadn’t been lubricated since it was built 50 years ago. I cleaned one and greased the other, and they both seem to turn fine.




I was less lucky with the motor alignment. For starters, I’d built in a slight twist; so the motor trolley wouldn’t sit evenly side to side on its track. I had to elongate the bolt holes in this coupling between the motor and quill about 3 degrees on the rotary table.




The motor trolley track is supported by the last cutoff pieces of the 6” channel iron. There was a high spot in the middle that the motor would not roll over, and it took several trial-and-error cuts to trim down the center supports before the movement was smooth end to end.

I spent the most on the electrical components. I rummaged through my old switches, but they looked and felt clunky. I thought the machine was looking coherent for an assembly of odd parts and spent some time picking and choosing a starter and enclosure that fit in visually.




Now we’re getting to the business end of the drill. The long travel and high spindle speed would whip the drill around without a support bearing close to the workpiece. I bored and reamed the bushing on the right using the ground shank of an R-8 collet as a bore gauge. It’s just under 1” diameter, so it should work with the smallest drill I plan on using. Then I used the R-8 collet like a mandrel to center and align the bushing in the lathe chuck. I turned the o.d. to 1.375” to fit the bearing and threaded it 16tpi for the retaining nut on the left.




I bored the support column for the bushing bearing on the lathe faceplate. I started out with a longer piece than needed so I could clamp it on both ends and for balance. Originally, I planned to cut off one end and bore the cut piece to make a clamshell housing for the bearing, but this is one of the best fitting bores I’ve ever made. The bearing tapped into the bore and refused to budge, so I decided to use it as it looks in the previous picture. I’ll see if it holds up.




The drill extension is a critical turning. I center drilled a 1” cold rolled rod both ends and set it between centers to true it end to end. Then I switched back to the 4-jaw chuck, centered it again, and recut the centers for a true alignment. At the same time, I drilled and reamed the drill end to 3/8” to hold the drill shanks. I’ll be using carbide tipped Forstner bits. I think the 3500rpm spindle speed would burn hss drill bits at the larger diameter. Back between centers, the chuck end was turned down to 5/8” with the very tip down to ½”. The tip will pass through the chuck, which has an open back, and into a centered bore in the spindle itself. With the drive dog on the chuck end, the extension is ground in a single pass end to end until it is a slip fit in the bushing. The compound is set to 60 degrees so the radial infeed is half the compound feed. There has to be just enough friction in that fit so the bushing will rotate with the drill extension as it passes through it. I expect a really serious person would heat treat this piece, but that is beyond me.




Everything is lined up to locate the bolts that will fasten the support bearing to the base. The quill moves easily through its full travel. The drill extension turns without binding, and the bushing turns with it all the way also. I did need to set some paper shims into the chuck to center the drill extension. Headstock chucks are a bit of a puzzle to me. They just have a single hole for a chuck key, and I wonder if this one is worn unevenly because of that.
	

		
			
		

		
	




I’m starting with a 1 ½” drill. The drill is advanced a bit to show the set screws that secure it.


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## hman (Jun 13, 2021)

What a fantastic re-use of a very stout casting ... good save!  And that's a great looking machine.

Will such a large boring bit (even carbide tipped) live happily at 3800 RPM ... or is that a 3 phase motor that you can slow down?


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## Papa Charlie (Jun 14, 2021)

So one thought I have, if the bit were to get jammed, maybe a knot or what ever cause, the only thing that I can see preventing the motor from becoming a rotating object is the gear rack. Would it be benefitial to provide some torshional control to the motor? It appears to be hanging on the quill shaft and supported by only the wheels.


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## JohnG (Jun 20, 2021)

I'm used to high spindle speeds with carbide tools.  I run 3" diameter shaper cutters at 8500rpm, so I think a 2" drill will work at 3500rpm.
The motor an quill weigh a ton.  I would not like to see them start to spin.  Hopefully, the drill would slip in the chuck and the breaker would throw before that happened.

The narrow base is going to need some side-to-side bracing. This has been a metalworking project so far, but for this the best material I have lying around is some 3 ½” thick blocks of laminated strand lumber I worked with in the 1990’s. I think the woodwork will complement the lines of the cast iron base with a couple of large mortise and tenon joints, tapers, and some corner rounding.




I used up an old can of polyurethane varnish as a primer and painted the brace with the same metal enamel I used on the casting. Most of the brace is on the back side of the base, away from the operator.




Finally, I really cleaned out my scraps to make the hold down clamp: cutoffs of reused steel channel left over from a previous project, a piece of black iron pipe, the end of a rectangular tube with some welds ground down, and a few tail ends of round bar stock.




Started out with a hole saw.




And finished with a boring head.




The clamp screw is ¾” x 6tpi stub acme. The screw thread is not as deep as a standard acme, so the bore in the nut is a bit bigger. I ground two tools: one for the screw and a very small one to fit in a ½” boring bar for the nut. The extra little bit of room in the bore was really needed to squeeze this tool in. I’d put a CBN wheel in the grinder since the last time I did close tolerance tool grinding like this. It put polished edges on the tools that I thought cut very clean for many light passes on the internal threads.




The first test bores. The clamp is very solid, and the workpiece didn’t shift at all either during the end or side boring. The intersections of the holes show the drill was boring true.
There’s always something about a first cut that’s unexpected. I hadn’t thought at all about how much sawdust these large holes would make.




From here on, it’s a woodworking project. I’ll make test joints like these using some redwood 1 ½” rods I made a long time ago. I’ll talk to a local guy who cuts tamarack timbers. In my minds eye it’s an open pavilion with a fancy roof and a fire hearth in the center—a place to sit on cold or wet days, which we have here in abundance, and enjoy my woods.  Thanks to all who provided comments.  Hope you found something here to enjoy.  John G


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## Papa Charlie (Jun 20, 2021)

John,
Impressive work, well thought out and executed. Thanks very much for sharing.


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## hman (Jun 21, 2021)

Truly a most wondrous sawdust factory!  Thanks for taking us along on your journey.


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