A different style boring head

No argument when it comes to boring heads the way to go is with a dovetailed slide with index-able adjustment screw.
But not everyone can afford to buy a good one or simply do not want to have to drive to the machinist supply store. So they make their own and several here on HMT.net have made some really great ones.
I am working on a project that is going to require 2 holes bored in 1 inch steel plate these holes will need to be somewhere in the neighborhood of 3.5" or just under 90 mm. SO I started digging around for some scrap pieces to make a boring head out of I found a cutout slug from a piece of ASTM 514 or T1 steel, about 1 1/2" thick and roughly 3 3/4" diameter perfect for the main body then I located a piece of cut off mystery round bar 3 inches long and 2 3/4" diameter.I'm pretty sure it was left over from some excavator pins I made but don't remember if I even knew what steel it was. anyway it was the only piece I had, this would work perfect for the sliding cutter holder.
I'm all set but there is only 1 little problem my dovetail cutters are packed away over 200 miles away. I called the nearest supply house that might have one about 85 miles away but they would have to order one if I could wait 2 weeks for it there would be no freight but if I needed it in 3 days or less it would cost me an additional $30.00 shipping. Forget that I said I could direct order one and have it in 3 or 4 days myself with no shipping charges.
But I'm not going to do that either. I'm going to make a boring head that doesn't need a slide dove tail T slot or other. I'm going to make a double eccentric and I'm going to make one that anyone can make who has a lathe and a drill press but little other specialized tooling.
to start off I cleaned up the slug to make it round with reasonably parallel ends. then I chucked it off center in my 3 jaw my reason for doing this was on my lathe it is a drama extreme to change from 3 to 4 jaw chucks then back again this can take an hour and a half due to the spindle nose on my Leblond lathe. Additionally I thought a lot of guys may not even have a 4 jaw chuck . To be honest after I had machined the eccentric bore I thought about I could have simply welded a short piece of shafting on the back of the cleaned up slug set off center where I wanted or needed it to be do the machining then saw it off LOL Hind sight always improves after the fact.
Next I recenter the part and machined a .500" groove for the tool holder lock.
Once that was done I cross drilled a 1/2" hole for the set screw I needed a 17/32" drill for the 5/8-11 thread but I don't have one, so I did the next best thing after drilling the 1/2" HOLE I ran a tapered reamer down it the reamer starts at .375 and ends at /625 I ran it in a little over half way then there was no problem tapping with a tapered starting tap
Next I chucked my tool holder block again off centered After machining it I noticed I had missed the offset by a few.000" and did not get a full round clean up I was going to leave it until I also noticed that I had transposed the distance of the locking grove which meant I had the groove in the wrong place by .125" which would mean my crescent shaped lock piece was going to be a problem.
New problem no more stock of this size so either have a sloppy under width lock crescent or weld up the surface and re machine it this would mean I could correct the previous offset mistake as well.
welded up and re machined now to bore the tooling holes Since I needed to offset even further I could not use a space block under one of the jaws so I clocked #3 4 turns of the scroll #3 is the best jaw to clock since when removing them for cleaning #3 is the first one that comes off and the last one to be put back on.
Next I tried to mill 2 flats for the set screws to secure the cutter tooling. the only end mills I had were 20 pc a set that was given to me last Christmas unfortunately they are better suited for milling soft air than actually having to cut steel. I had used a couple of the 2 fluted ones on aluminum nut had never tried to mill steel other than what I knew to be mild steel or 1018 cold rolled On this stuff though even with coolant the HSS end mill only managed to make 1 cut before becoming so dull it wouldn't do anything. SO I put a short carbide tipped boring bar in a collet then finished making my flats then drilled the 4 holes with a 5/16" cobalt drill bit. Tapping to 3/8 16 was an adventure but I managed without breaking a tap
Next was to make the crescent lock piece . this was made from a piece of cylinder I found laying around that had roughly the correct inside diameter I cut a segment then ground the outside to shape
Finally the assembly and a mock up test to check the cutting range. it turns out that in the outer most hole the range is from about 2.5 to 4.25"
I'm happy and will be really happy when I see it bore the parts I need.
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Thanks Frank S! We've added your Boring Bar to our Machining category,
as well as to your builder page: Frank S's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-boring-bar-23"> <img src="/uploads/203558/homemade-boring-bar-23.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-boring-bar-23">Boring Bar</a> <span> by <a href="http://www.homemadetools.net/builder/Frank+S">Frank S</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/boring-bar'>boring bar</a> </div> </div> </div> </div>
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Nice original approach Frank, I would not have thought of that.
Is desperation the mother of invention perhaps?.

olderdan, to coin a phrase a mans got to do what a mans got to do. While it may not be as user friendly as a more conventional dovetailed slide it is very stable due largely to both eccentrics having a close fit and the crescent lock fits snugly in both the head body and the tool holder groves pressure from the set bolt which I will be changing out for a regular set screw the next time I manage to go to a good hardware store only needs light pressure to securely lock the 2 parts together.
I figured out that later should I decide to do so I can mark indexing lines around the tool holder and place a single mark on the head which will make it easier to see how much to rotate the holder for a given bore diameter.
I can put a real short carbide tool in it and use it as a single point surface or tramming mill head so I am more than pleased with the outcome even if it does look hoggy I wasn't tying to win a beauty contest with it

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Originally Posted by Frank S

olderdan, to coin a phrase a mans got to do what a mans got to do. While it may not be as user friendly as a more conventional dovetailed slide it is very stable due largely to both eccentrics having a close fit and the crescent lock fits snugly in both the head body and the tool holder groves pressure from the set bolt which I will be changing out for a regular set screw the next time I manage to go to a good hardware store only needs light pressure to securely lock the 2 parts together.
I figured out that later should I decide to do so I can mark indexing lines around the tool holder and place a single mark on the head which will make it easier to see how much to rotate the holder for a given bore diameter.
I can put a real short carbide tool in it and use it as a single point surface or tramming mill head so I am more than pleased with the outcome even if it does look hoggy I wasn't tying to win a beauty contest with it

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nice work,I ma ke most of my tooling. I would however drill through the center and use a resesed allen head locking bolt to pull the assy up to the main body firmly witch should take out any deflection/movement& possiably chatter. I suppose the key & groove could also of been tapered to help lock it down firmly not just size wize ( kinda like a lock down anglock vice) over all very nice work.I hate when you have to weld up stuff from a goof. I try to make prints and work it all out ahead of time, but that never works out 100% either. And there are always upgrades that come up during manufacturing when the brain kicks in to high gear.....or forgets important stuff.

marksburg the head works fine the lock key seems to hold it tight enough one problem I have with it is the Mill itself does not have a slow enough spindle speed for using a boring head in a torched cut hole. So to prevent knocking any more tops off of my boring bars I am going to have to pull the plates off the mill then run a cob grinder through them to remove the heat effected layer the steel plates are made out of ASTM 514 so it is hard and tough to begin with. I really need something in the 85 to 150 RPM range for making the first rough cuts instead of the 560RPM bottom speed of this mill. interrupted cuts are murder on cutters and couple that with a torch hardened surface of the inside of the holes it only gets worse from there.
I may wind up and do a set up on my lathe with the boring bar I made for it to bore these plates I already know that works on hard tough steel such as this.
I did a cad model of the boring head in Solidworks I looked at trying to use a bolt to lock the 2 parts of the head together but with a double eccentric there is no common center-line so the crescent lock key was about the only solution tapering it would not have improved it but placing 2 spaced 120° apart would have done some and if I see there is an issue later on I may add another groove and a 2nd lock as the head is figgley to make fine adjustments

only one center line needed to lock togeather. you can thread the body offset hole in the center of it.and go through the center of the smaller round bit/cutter/boring bar holding peice, to hold it. or go through the top if it's offset far enough to clear the shank and tap the smaller bit holding portion. I suppose a second holding lock key could be positioned a third of the way for added support if the through bolt dosent have enough room due to the amount of offset & bar hole size. 2 keys is like a chuck it givs 3 places to hold to keep any vibration or cocking down to a min,thats also why I like a tapered lock down key to help keep it planted.there is a lot of stress and vibration as you see with it killing the cutters on flame cut material, that may be helped some Im not sure, remember only 1 holding key can make a pivot point fir the assy to"rock" in the main body as it contacts the material. I love your idea & work. lately Ive been buying some of the china made cutter heads with multiple indexable incerts(witch are also super cheep coming out of china), there cheep and well made and can be modifyed eazely too. if you had a size that you normaly flame cut then used the boring head one of those close to that size and possiably use it to knock out the flame cut then final size with your boring head. I hate buying china but at 1/8" the cost......I aint no big corporation. and even finding what I need from the normal suppliers ...iffy at best.and most of the time unafordable... ebay & bangood.com is my friend.....and many are free shipping. $6.00 box of 10 incerts with free shipping....and as of yes Ive had no issues with the incerts.Ive probably bought 15 or more boxes of various incerts this year already along with cutter heads,boring bars, tool holders for the lathe, end mills etc, all with various change able inserts. and many of the inserts are name brands,or using Mitsubishi materials& coated else where. keep up the great work!!!

also with the indexable inserts&bars there are somany different grades, you might just find one that will cut without dystroying it. rough cut, rotate insert,final finish cut.
as for the mill speed, look at building a jack shaft& extra pully&belt to get the speeds you want, you have the brains&capability to do so!!! I too need a slower speed on my BP....well BP clone, 1979 millport 9x42 ,I did have a small auxzillary motor off the side of my small 1975 enco mill for slow speed stuff.But thats sitting un powered and in the way....along with a lot of stuff in the way.

the jpegs of my drawings may help to see how the assembly is put together
You are correct if I were to drill through the main body on the center line of the bore for the tool head there may be just enough room to place a socket head bolt and drill / tap the tool head on that center-line as well
Thanks sometimes we don't see the forest while standing under a tree
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the tool head toes not have the tooling locations drilled all the way through so it is possible to add the set bolt

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I have some of those trees in my yard. I once worked in a prototype shop, programing&running the cnc mills off prints and out of my head. many times the prints were rong...especilay when the owner (engineer,machinist etc) did them.... or when they were done by a engineer that did not know basic real life things like...bend raidi changing locations when things are machined then bent and different thickness material alters that also... aerospace, defense engineering ****.....sometimes I wonder weather they can get thier zippers down before or during or after the peeing down their own leg process begins.( male&female, engineers). those sure are pretty pictures(cad) I dont do any of that stuff hear at home...the only place I work any more.I probably should. be eazer to remember stuff than paper.

Well I am off to plan "C" the idea of placing a set bolt in the center would only work for up to about a 1/4-20 without having to cut into the center shaft that goes in the collet and I feel that anything less than a 3/8-16 would not do much if I ever needed to use a longer boring bar cutter like for going into 3 " or so, and should I go ahead and install the 3/8" diameter bolt the relief area required for the head would require me ot mill away a notch that would remove nearly half of the shaft which would weaken it too much for comfort. So I will have to install 1 or 2 set screws at angles to the original lock.
Another thing I noticed after grinding the plates and trying the boring head again was as long as I force myself to take very tiny cuts it works great, however I noticed that I have quite a bit of slop in the quill bearings so I am going to have to deal with those soon.

a real good quality1/4 or even 5/16 grade 8 with a hardened wavy washer under the head.will do a lot more than most people think torqued at only 14~18 pounds on that short of a bolt. as far as the 2 extra set screws, either use a "puck","key" something to keep from making an impression and making adjustability a chore. of coarse hardening the entire thing would also be a good way to keep brinelling&deformation ( boogering up)to a minimum. I tend to get impatent and dont like a lot of little cuts....thus..I sometimes swear a lot when something gets cut toomuch...., my worst thing seems to be making a new tool and not marking it for what it is and...sometimes it gets grabbed thinking it's a drop or whatever and... turned into annother tool...with out realizing it. especialy on round stock Ive made to hold something inpaticular to machine that part......and when Im done...ferget to mark it for what it is. sometimes scraps... are not realy scraps. I do repourpose a lot of stuff, like engine parts...forged piston tops are sweet for oh somany things. camahafts are great for many things too, but be carful if you try to cut the lobes off with a lathe it will beat the **** out of the lathe, those lobes are hardened. I started using a chop saw to cut the lobe's down before sticken in the lathe. keep on making and posting good stuff.we all need new ideas. even just seeing something gets our minds to wandering on something we havent thought of that isant the same but might have just 1 part that will set things in motion. as for the quill bearings....that tree your having lunch under is on a path that has no end.....

Another really interesting thread, thank you, Frank and Mark. I walk that path daily. Haven’t even mastered carpentry, or ever really stated machining metal, what a lot there is to learn!

This thread is old enough now that I guess it needs an update. Some of my observations after I made it and used it several times. #1 it is not as easy to index for bore diameters as a dovetail head would be. #2 after through drilling it from the bottom part into the top part and threading it for a 5/16-18 clamping bolt it did help with stability #3 the range of adjustment as I made it was a little lacking This could have been overcome by making the whole thing a larger diameter with slightly more eccentric offset and if I were to make another one like it, I would make the eccentric stem longer for stability. However, if I were to make another, I probably wouldn't use the eccentric design at all just take the extra time and make a dovetail boring head, the problem with that though is I still don't have any dovetail cutters.
Ther is a consolation to a design of this type though. For someone with limited tooling or experience a boring head such as this would be an easier build and with some careful measuring you can achieve satisfactory results for about any bore you need to make providing you take your time. I am a little too impatient at times when it comes to running a mill, I just want to hog my way through the initial cuts and do a single final cleanup like I can do on a lathe, which is not a good practice especially with smaller machines I'm a T50 or MT7 type guy. The concept of an ER11 collet is as foreign to me as a bb gun would be to a gunner's mate on a battleship

dove tail cutters are great.hell use a fly cutter as a dove tail cutter, but go slow and if possiable one side of the tail at a time. my brother hits a lot of swap meats..oops meets. Ive been to a few with him there are always guys there with old machining tools&tooling. he has been buying the big lather indexable holders (1"square and larger,mostly about 1.250 to 1.500 shank size, and he mills a slot in them and then dove tails them and adds a stop screw for hight adjustment. to used them directly on the quick change fixture on his lathe, no need to buy a bunch of holders. I was quite impressed when I saw what he was doing with them when we got back to the shop. and he only pays 2-$5. each for them many times a lot less when he offers to but a whole pile of them and other things ,he go's buy early and looks, them late he makes the offer "Ill give you$$ for all that stuff and you wont have to pack it up and haul it back home just to toss it..... and it works every time. and his offer is usually less than what most would pay for 1/5th of it. he has so much tooling and machines now that I doubt he will never be able to use it all.
As for me....I've stopped buying stuff, I have realized that my limitations and my wants and Ideas, and what I will actually get to do are 5 different things. my days of most of that are over. my mind wants to do it all,sees how it all needs to be.... but my body & drive just aint into it. as well as memory. 1 min it's all there 2 min later its' gone outa my head.

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Originally Posted by Philip Davies

Another really interesting thread, thank you, Frank and Mark. I walk that path daily. Haven’t even mastered carpentry, or ever really stated machining metal, what a lot there is to learn!

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carpentry is easy.. well for me it is. as long as it's building buildings, Im not into cabnet work.those are easyer to buy on clearance and stick them in.work benches&storage yes thats easy, like building building. my 24x34 shop 6' from my bedroom back door took my about 2 months to build by my self(I did have somebody else do the concerate after I did all the form work to make sure it was square&level. it's fully sheet rocked,central ac&heat, bathroom,kitchen,engine build room, blasting&porting, grinding room too. then I built a 12x12 for my 4 wheeler&dirt bike&wood worken stuff, then about 2 years ago ai built my 11x16 2 story barn, with ac for storage and my wood worken tools will be in there as well as painting ****. all that stuff is eazy to do. especialy if you have atleast half a brain( witch is more than 90% of the guys doing it nowdays) I always over build everything. extra huricane straps&brackets & more. I kinda like building stuff with wood nowdays it's lighter and easyer to clean up than the mechning stuff.....and more relaxing too. well it was befor all the price gouging started 2 years ago . ****ing $6.48 sheet of osb now $50.I have a lot I want to do but not at those prices. Im done.

As far as carpentry goes I try to avoid it, That's not to say I can't do it I just prefer to burn wood rather than work with it

Quote:

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Originally Posted by marksbug

also with the indexable inserts&bars there are somany different grades, you might just find one that will cut without dystroying it. rough cut, rotate insert,final finish cut.
as for the mill speed, look at building a jack shaft& extra pully&belt to get the speeds you want, you have the brains&capability to do so!!! I too need a slower speed on my BP....well BP clone, 1979 millport 9x42 ,I did have a small auxzillary motor off the side of my small 1975 enco mill for slow speed stuff.But thats sitting un powered and in the way....along with a lot of stuff in the way.

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Everyone calls you Marksburg. I kinda get a kick out of it.

Quote:

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Originally Posted by Frank S

This thread is old enough now that I guess it needs an update. Some of my observations after I made it and used it several times. #1 it is not as easy to index for bore diameters as a dovetail head would be. #2 after through drilling it from the bottom part into the top part and threading it for a 5/16-18 clamping bolt it did help with stability #3 the range of adjustment as I made it was a little lacking This could have been overcome by making the whole thing a larger diameter with slightly more eccentric offset and if I were to make another one like it, I would make the eccentric stem longer for stability. However, if I were to make another, I probably wouldn't use the eccentric design at all just take the extra time and make a dovetail boring head, the problem with that though is I still don't have any dovetail cutters.
Ther is a consolation to a design of this type though. For someone with limited tooling or experience a boring head such as this would be an easier build and with some careful measuring you can achieve satisfactory results for about any bore you need to make providing you take your time. I am a little too impatient at times when it comes to running a mill, I just want to hog my way through the initial cuts and do a single final cleanup like I can do on a lathe, which is not a good practice especially with smaller machines I'm a T50 or MT7 type guy. The concept of an ER11 collet is as foreign to me as a bb gun would be to a gunner's mate on a battleship

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Sounds like you need a small shaper. They say you can make anything but money with a shaper, but there are some things you can't do with anything else, and the cutters are pretty cheap.

Bill

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Originally Posted by WmRMeyers

Sounds like you need a small shaper. They say you can make anything but money with a shaper, but there are some things you can't do with anything else, and the cutters are pretty cheap.

Bill

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I have actually thought about buying or building a shaper Haven't found one that would be within my budget for one or found the extra time to construct one from scratch for two.

Ive seen a lot done with shapers, one of my old bosses tryed to give me one, it was in the way,I did not have a clue what it was or could do.

An 'adjustable' cutter is fairly easy to preset a specific diameter, even a flycutter. Set up the holder in a Vee block, clocked vertical with plane of cutter slot. Use height gauge to figure centerline of shank, add radius of desired diameter to centerline. This works quite well in square/ rectangular tubing. I wouldn't expect bearing fits, but .001-.002 for weldments of round tubing, rods etc easily. Our technique for machine frames, put holes in first with hole saw [CRS 1018], and two bore passes, first as a primary to overcome ragged saw cut. To lessen tool changes, table had two equal vises and a stop bar for material, swapping them instead of tools.

'They' say can't make money with a shaper.....but watch prices on a Bridgeport attachment, [usually $1200 USD] or a real shaper of 20" something stroke, upwards of $2.5k. I'd say some folks have a better idea how to utilize them, and have room. My rule of thumb; stroke 3x widest cut anticipated. That's adequate rigidity for key ways and such. Planing/ profiling cuts aren't so demanding.
Can't count the Atlas etc, good little machines and capable, but there is a complete hobby engineer crowd chasing those at outrageous prices.