Clark Tool Co. Adjustable Boring Bars

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.The question, the main point of this post, is near the bottom!Some time in the distant  past, I acquired three boring bars and a selection of cutters made by the Clark Tool Company, and one carbide-tipped cutter from another firm. These bars have rectangular slots through which an adjustable blade fits; the blade is made of two halves partially overlapping each other, the distance between the two ends being adjusted by a screw and the two being clamped together by another screw. A pin in the bar fits into a groove in the back side of the assembly, allowing it to self-center but still be retained in the bar. The pin is initially inserted through the front of the bar but when in use, sits between the back of the blade assembly and a cam which is inserted into a hole behind the slot. The pin is held captive by a setscrew; neither  is shown in my sketches below.   I have looked online but found essentially nothing about the Clark Tool Company except that in 1997, according to this Alvord-Polk Website,   "A continuing desire to expand the current cutting tool offering led to the acquisition of the Clark Tool product line from the Cogsdil [sic] Manufacturing Co. of South Carolina in 1997" by Alvord-Polk. When I called Alvord-Polk, the fellow in Customer Service didn't know anything about either my bars or about the Clark Company. I may try contacting Cogsdill next week. In the meantime, I thought I'd see if any of the old-timers here were familiar with these bars. Newer but sort of similar  (e.g. APT ) bars have the locating pin/screw holding from the front.I took some pictures of the bars and cutters last week, but haven't gotten around to downloading them yet.  My bars are in three diameters, using either two or three different sized cutters. The larger 3/4" bar is complete, but the smaller two are missing the hardened cams which are both ~0.187 OD, and 0.35" long. [I think the sketch is wrong]I want to make two of these cams and have an idea how to make the 1/16" blind hex hole without using a standard broach. I was wondering how members here might do this, using only homemade or 'home shop / hardware store' equipment. I'll give my idea later....Maybe I'll get the pictures downloaded later too.
Reply:Good morning Oldiron,I'll have to look at the shop and see if I can find my "hunt broach" tool and post a pic (this tool converts rotary motion to an axial wobble and cuts 360 with a pre-dilled hole).I have never hand broached or slotted a feature that small, but it can be done manualy with a lathe or the quill on a bridgeport type miller. It helps to have a through hole for the shavings to exit. I always thought it was easier to hand broach a small keyway in a tapered bore on the lathe, rather than make the setup on a shaper or slotter (now a mitts&merrill keyseater with a sine table is a different story).Matt
Reply:I've seen allen sockets  that appeared to have been "skived".Chips are left still attached in bottom of blind hole.Last edited by jpump5; 01-23-2011 at 08:52 AM.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:Originally Posted by Matt_MaguireGood morning Oldiron,I'll have to look at the shop and see if I can find my "hunt broach" tool and post a pic (this tool converts rotary motion to an axial wobble and cuts 360 with a pre-dilled hole).I have never hand broached or slotted a feature that small, but it can be done manualy with a lathe or the quill on a bridgeport type miller. It helps to have a through hole for the shavings to exit. I always thought it was easier to hand broach a small keyway in a tapered bore on the lathe, rather than make the setup on a shaper or slotter (now a mitts&merrill keyseater with a sine table is a different story).Matt
Reply:can't you drill and braze a hex shape inert in place.
Reply:With just home shop tools grind a broach from HSS and push it in using the quill of your mill or the tail stock of your lathe. to get the hex correct use a simple collet block set. being only 1/16 you will not have a very big chip load.LarryMiller XMT 304 CC/CVSyncrowave 180 SDLincoln PowerMig 255XTTermalDynamics 52Lincoln 305GComlpete machine shop to back it up
Reply:Doesn't help you build 'em but...  your description strongly puts me in mind of some of the old Bullard tooling we ran (only ours was a hair bigger lol) - you might run your research that way when you get bored and se eif you cant find any new old stock around - not likely but you never know.Loved them old machines, the way a window loves a rock.
Reply:Originally Posted by Oldiron2Also, I meant to specify no fancy commercial tools like broaches, but simple homemade ones are allowed.Is the "hunt broach" anything like a multiflute drill which wobbles around in a hole and produces one more lobe than the drill has flutes?  "how would you do that in a 'poorly equipped' home shop"? Let's assume I don't even have a good press  ( I don't, either).
Reply:Originally Posted by Matt_MaguireGot you Oldiron, If you have a lathe or small mill they can be used like a slotter. I'm not sure you wouldn't be better off starting with a "stripper" shoulder screw and turning the features on the outside."hunt broach" is also known as Swiss rotary broach like below (in case you ever see one at auction etc). Good luckMatt
Reply:I guess I cheated when I needed a hex hole.  I sacrificed a deep wall socket and cut the waste end off where the rachet goes.  I then roughened and cleaned up the outside of the socket for the brazing to lock onto.  It was a black oxide impact socket so no chrome to worry about. I fluxed it and brazed it in the hole I drilled and reamed by hand.  One other time I chamfered the hole and beveled the outside of the socket and welded the socket in place.I know this doesn't help you in your quest I just thought it might help some one who is needing an easy alternative for a field repair.
Reply:Originally Posted by Oldiron2Matt;I don't see well enough to work with corners in sixteenth inch holes anymore and anyway, it sounds like too much work, even on a 2J Bridgeport. I thought about starting with a fastener, but the hex hole is way undersize for anything big enough to turn down.That's a pretty neat idea about wobbling so only one point works at a time. It would be great for production work in a small shop, probably fairly cheap to get different 'broaches' for new jobs...but not cheap enough for a one-of-a-kind job for me. Wonder how the tooling compares in cost to standard broaches?What I plan to do is to find or make a short piece of tube to fit 'loosely' over a 1/2" or 3/8" rod, then drill and press fit a short piece of hex key into a plug to be fitted to the top of that guide tube. I might just hold the lower section of the tube with Vise-Grips when in use. I might even try pre-drilling the stock rod a bit, if only for better centering purposes.(snip) The hole should be parallel to the stock too. Just need to get it apart again before the metal shrinks or hardens.
Reply:Since your going to machine after punching, then how about making a couple of sacrificial jigs that fit closely and machine them away.  I interested in seeing the results.
Reply:Originally Posted by tapwelderSince your going to machine after punching, then how about making a couple of sacrificial jigs that fit closely and machine them away.  I interested in seeing the results.
Reply:I have done it by taking a socket head cap screw the right size and silver soldering it in a round hole. you can even turn a little off the OD of the cap screw head if and make a press fit that would probably work.Lincolin Power Wave 450, Lincoln Powermig 255, Lincoln Pro Mig 140, Lincoln Squarewave Tig 275, Miller Big 40 G(with Hobart Hefty suitcase), Thermal Arc 95S and Esab PCM875 in an already full machine shop.
Reply:I was referring to your tubing/hex key setup as a jig.  If there is concern about swelling, then make a close fit and machine it off if it upsets too much to slide off.  Seems as though you would end up closer to the end product-- centered and parallel.
Reply:Originally Posted by tapwelderI was referring to your tubing/hex key setup as a jig.  If there is concern about swelling, then make a close fit and machine it off if it upsets too much to slide off.  Seems as though you would end up closer to the end product-- centered and parallel.
Reply:Drill and tap all the way through, put a 6-32 set screw in and weld/solder/braze/locktite it in place? You could also do a blind hole and use a bottoming tap or just cut a tap in half to thread right to the bottom.Last edited by Brad Blazer; 01-26-2011 at 11:12 PM.Lincoln SA200, HH135, Lencospot, HF80 Inverter, Rockwell 11x35 lathe, HF drill mill, Kama 554 tractor w/ FEL & BH, Belarus 250AS, lot's of Chinese tools
Reply:Originally Posted by Brad BlazerDrill and tap all the way through, put a 6-32 set screw in and weld/solder/braze/locktite it in place? You could also do a blind hole and use a bottoming tap or just cut a tap in half to thread right to the bottom.
Reply:Originally Posted by Oldiron2I want to make two of these cams and have an idea how to make the 1/16" blind hex hole without using a standard broach. I was wondering how members here might do this, using only homemade or 'home shop / hardware store' equipment. I'll give my idea later....
Reply:Originally Posted by forhireI have a rotary broach from Slater Tools that works great. The broaches aren't too expensive but holder was expensive. Like Matt, I don't have any broaches that small. Too expensive for just a few parts. Maybe you know someone with a sinker edm that could do the hex easy. I like your home forging idea. Your small form may not hold up. What if you pre-drilled the part and then pressed in your form hot? Not a truly forged part but likely equally as strong as broaching.Maybe I missed this in the thread but does the part really need to be blind? The part is so small, it may be easier to just broach through. A lot of these small cams are broached though... it would give you more meat and less chance of stripping.
Reply:Oldiron, you're starting to sound as picky as me... Might be getting on my nerves...If a slot and a well made spade driver got us where we are now... Why not???Matt
Reply:Originally Posted by Matt_MaguireOldiron, you're starting to sound as picky as me... Might be getting on my nerves...If a slot and a well made spade driver got us where we are now... Why not???Matt