Deep Drilling In aluminum block

[Bentwings]

I meant gun drills sorry


also try graingers

Also try
Guhring gun drills
And msc

and sterling gun drills

hopefully one of these will ship to you.
byron

 

[mayhugh1]

Hi everyone,

A while back I purchased the Martin Ohrndorf V-12 plans. I've been studying them for a while to get an idea of the construction. I found a supply for 7075 aluminum for the crankcase at a reasonable price. One part has me a bit stumped so I'm trying to wrap my head around the problem before considering starting the project.
The main bore is 42mm through the crankcase which is approximately 8 1/2" long. I've been trying to find a 1.5" drill bit to have a starting point for line boring but usually the bits are way too short on unreasonably priced.

At my disposal I have a Bridgeport and a 13x40 lathe. My first thought was mount the block on the carriage and find the right drill bit and mount that in the spindle. Then leave the setup and install a line boring bar to get to the final dimension.

The crankshaft has aluminum bearing supports, which match the 42mm hole diameter and have press fit bearing. The consistency of the holes seems more critical than the dimensionally accuracy as these parts can be made to suit.

Thank you for any feedback,
Kyle

Maybe leave some excess stock on all sides of your workpiece so you can re-square it around the hole if drilling wonders off. - zterry

 

[ajoeiam]

I meant gun drills sorry


also try graingers

Graingers likes to price its stuff in the platinum/palladium category in my looking!
Great for big outfits that want to single source but not very friendly for little folks!

 

[Bentwings]

Graingers likes to price its stuff in the platinum/palladium category in my looking!
Great for big outfits that want to single source but not very friendly for little folks!

If you look on he internet under blondiehaks you tube there is a good video and explanation of how she did a lone bore on her lathe. By the way she does some excellent work and explains ans mistakes and how she fixed them she is an excellent model machinist and a young lady besides. I worked with a “ roadie the riveter “ type woman in my early years she was all navy flaming red hair and personality to match. Very good machinist. Too. Blonde has a smaller lathe Ethan yours so you might have to work at the extreme limits and make your own boring bar but it can be done.
Byron

 

[Bentwings]

If you look on he internet under blondiehaks you tube there is a good video and explanation of how she did a lone bore on her lathe. By the way she does some excellent work and explains ans mistakes and how she fixed them she is an excellent model machinist and a young lady besides. I worked with a “ roadie the riveter “ type woman in my early years she was all navy flaming red hair and personality to match. Very good machinist. Too. Blonde has a smaller lathe Ethan yours so you might have to work at the extreme limits and make your own boring bar but it can be done.
Byron

im sorry I didn’t mean to toss something out that you might not know about.
Gun drills are usually long single flute drills. Often hollow so cool at can be plumped through them drill pints are ground to be self centering like split point you usually center drill and maybe counter sink a short ways to get started. Obviously they are long skinny things so you have to be gentle drilling small holes. You need to make sure you are cleaning chips out too . The coolant hole using pressure helps flush chips out. It takes a fancy holder/ spindle arrangement to provide coolant though the drill. You cal do manual drilling as long as you can clear chipset often a lot of cranking drill handle up and down . It’s been awhile sinice I’ve used them but I’ve done some small long holes over the years early car crankshafts didn’t always have the best oil holes they are tough materials too . Often these are carbide tipped but with nice cutting edges already ground in they drill pretty well

byron

 

[giel]

sandvik-coromat they havr them in the collection deep hole drills.. but you can also do it what they call kotteren in the Netherlands.. using a smaller drill and offsetting it you can drill holes 40% wider than the drillbit,big advantage is the chips can exit very easy and it aids in precision

 

[kylenlord]

Thanks again for all the feedback guys.

I think at the very least Terry's approach is spot on. I made sure to get a big enough block that if the drill should wander, there's enough room to account for everything else.

Petertha, very nice job on the rendering. I may do the same in fusion. I'm toying with the idea of cnc routing the top deck features. I'll have to do some practicing first. I do have access to McMaster through my work. Most of my materials and tooling comes from them. We work in small enough sizes most materials don't break the bank.

By any chance did you look at how the intake and exhaust tubes mount to the heads? The plans basically say to glue them in, which I would want to try for something more elegant.

Bentwings, thank you. Yes I follow blondie hacks on Instagram, I'll go back and review her video on line boring. I saw she was making a steam engine which is pretty neat.

Thanks again everyone
Kyle

 

[petertha]

By any chance did you look at how the intake and exhaust tubes mount to the heads? The plans basically say to glue them in, which I would want to try for something more elegant.

I didn't get that far in the assembly model yet, but you've raised another good point I was pondering. His radials use a threaded nut screwed into the head for both intake & exhaust. The nut presses on an upturn or pipe flange (and in my case, a Teflon washer between pipe & head flange). I strayed from the design a bit, but same basic concept.

I noticed no thread callouts on the V12 heads which I took note of as potential oversight and maybe 'glue' could mean 'sealant' in translation. He doesn't make (many! LOL) mistakes so I wonder if the V12 lends itself to permanent tubing extension 'stacks' that can be assembled & sealed to the manifold itself, mitigating these nuts altogether. It would simply things because my experience with the shallow counterbore + odd angle port axis into head + shallow bottoming threads + sealing the pipes is a collective PITA. I told myself next engine will be flanged & screwed one way or another. Even the radial was challenged in that respect as the flange screws & valve cage features & other issues didn't want to play nice together. On one hand I can see mini pipe stack being easier, but I can also think of some disadvantages.

(pic) FWIW I did some experiments bonding aluminum unions to the pipe. I didn't have to go this route but it could be a way of fixing pipes into position, kind of like a glue version of silver soldering. This was JB weld but flavors of Loctite would work well.

 

[petertha]

I looked on AliExpress & some of my other offshore haunts for less expensive spade drills. They look to be +/- the same price as N-Am offerings. If I did a lot of this kind of work it might pay to buy an arbor. The replaceable cuttters are reasonable but arbors come in bracketed diameter & reach ranges, so one would have to be choosey because they are spendy. Shop making the arbor is another option if one were so inclined

In my KBC catalog I found several good, conventional drill candidates in the $35 range that could pilot drill the crankcase half way from both ends. I don't think it has to be a pretty hole, just enough to pass a line boring bar through. And even if 2 line boring bars were required (slim & larger/finisher) probably still a cheaper way to go. It looks like the process will require lots of incremental cutter adjustments in any event, so will take some time to get it right.

I cant think of a good way to make a split case in order to hog out the core with end mill & permanently bond the halves together before line boring. There just isn't a lot of sidewall meat for pins & screws & such.

 

[william_b_noble]

Awesome, thank you everyone for the feedback!

I think from what I gather, I'll grab at minimum a 1"x 9 or 12" drill and plan to drill from the headstock with the piece mounted on the carriage. Then line bore to the finished dimensions. Pethertha, I'm glad to hear that I wasn't the only one pondering this issue. A friend of mine does have a taper adapter that would let me put a mt bill into my headstock. I'll see him tomorrow and find out what he has.

Jkimberin, I am in chilly Rhode Island. Hoping the weather will be picking up so I can finally get back out into the garage.

Thanks again everyone
Kyle

I think, if I understand your words, that you are making a mistake. you want to hold the block (the thing you are drilling) in a 4-jaw chuck wiht the place where you want the hole centered on the axis of rotation, and hold the drill in the tailstock. That way if the drill wants to wander, the work is rotating so it wanders in a circle which is a close approximation of the hole you want, rather than making a left turn and heading out to the edge of the block. Once you have the starter hole, ream it to exact size and then use that hole as your reference for all other work.

 

[william_b_noble]

I looked on AliExpress & some of my other offshore haunts for less expensive spade drills. They look to be +/- the same price as N-Am offerings. If I did a lot of this kind of work it might pay to buy an arbor. The replaceable cuttters are reasonable but arbors come in bracketed diameter & reach ranges, so one would have to be choosey because they are spendy. Shop making the arbor is another option if one were so inclined

In my KBC catalog I found several good, conventional drill candidates in the $35 range that could pilot drill the crankcase half way from both ends. I don't think it has to be a pretty hole, just enough to pass a line boring bar through. And even if 2 line boring bars were required (slim & larger/finisher) probably still a cheaper way to go. It looks like the process will require lots of incremental cutter adjustments in any event, so will take some time to get it right.

I cant think of a good way to make a split case in order to hog out the core with end mill & permanently bond the halves together before line boring. There just isn't a lot of sidewall meat for pins & screws & such.

just make the drill - it's really easy - get a lengt of tool steel of the diameter you want, grind a D-shaped point and then harden and you are good to go

 

[mcostello]

How is a ball endmill better than a properly sharpened drill bit?

 

[peterl95124]

I would modify the design to use split bearings, both the half-circles in the block and the half-circles in the bearing caps are milled with a ball-end mill. Every IC engine I've built is done this way, I even modified the DeHavilland Cirrus I'm making to be this way. Remember, plans are only suggestions !!!

 

[william_b_noble]

I would modify the design to use split bearings, both the half-circles in the block and the half-circles in the bearing caps are milled with a ball-end mill. Every IC engine I've built is done this way, I even modified the DeHavilland Cirrus I'm making to be this way. Remember, plans are only suggestions !!!

why would you use a ball end mill? that just seems so wrong - a side cutting end mill on a rotary table maybe - can you explain what I'm missing here?

 

[peterl95124]

why would you use a ball end mill? that just seems so wrong - a side cutting end mill on a rotary table maybe - can you explain what I'm missing here?

my apologies, sorry for the confusion !, I'm not talking about using the end mill as a drill,

put the crankcase in the mill vise so the crankshaft, if it were in there, would be horizontal,
then run a ball-end-mill horizontally to cut half-circles where the crankshaft will go,
but use a ball-end-mill that is larger than your crankshaft journals so you can fit split bushings in,
then make bearing caps with similar half-circles that bolt to the crankcase after the crankshaft
and split bearings are in place, hopefully the photo below clears things up

the difficulty in getting a smoothly turning crankshaft in a model engine isn't the
alignment of the bearings in the crankcase (people are unnecessarily obsessed with
line-boring, like is sometimes used in full size engine rebuilds), rather it is in getting
a trued crankshaft, the crankshaft always bends when placed between centers on a
lathe and nothing comes out right unless you take precautions, turn every journal 30-thou
over, then machine your webs to final, then turn every journal to 10-thou over, then to
1-thou over taking very light cuts with as little tailstock pressure as you can do with,
then use abrasive paper (with oil) through finer and finer grades to polish down to final.



this is an inline (my Duesey), but did the same for my V12 Merlin,
this shows the relative orientation of the ball-end-mill with respect to the case,
and what split bearings and bearing caps look like.

 

[Richard Carlstedt]

How is a ball endmill better than a properly sharpened drill bit?

Let me address that particular question exactly and not infringe on Peters explanation.

First --let me say that Ball Endmills are made far more accurate than any drill bit.
Just look at the sharpening equipment used to produce the ball , not only correct diameter but a perfect spherical cutting surface. I have seen brand new factory drills with mishaped configurations
Second-- look at a regular endmill and notice they cut on the outside before the center touches metal _ Why.. because the ourside gives stability to the true center location, in other words, the outside of the flutes render guidance
Third-- Drill bits are Longer than endmills, Right ? well that makes them flexible, which means they drift.
Forth-- But you say, I use a center-drill first ...wrong, (!) center-drills are for making center holes for tailstock live/dead centers and are completely inappropriate for starting holes...why ?------
because they do NOT match drill point center angles 60 versus 118 . If you want to match the drill point, use the appropriate "Starting Drill " ( shorty and matched angles) for more accurate drilling
Fifth-- Starting with a ball mill (no predrilling) means the ball mill is not affected immediately when it touches the surface , which means metal variations/inclusions have no affect and the very face of the ball mill is like a facing operation before the plunge , this means the mass and rigidity of the ball cutter is used to get perfect centering on the workpiece and the amazing thing is as it penetrates the metal , the sides further up the ball , nearer the OD, actually can shift the cutting center to match the true center of the ball endmill.
Sixth-- Ever wonder why drills come in 118 and 135 angles ? it has to do with cutting load and materials , and the 135 is more rigid and which is closer to the ball endmills construction

Hope this helps you and others understand the value of ball endmills
I spent over ten years running a gundrilling operation , drilling up to 48 " deep on stationary 4140 dies which is more difficult than using a gundrill lathe for getting accuracy and we did all kinds of tests and evaluations, and by far , the most accurate and concentric holes were ( started) achieved with Ball endmills, and which sometimes even required the cutters be custom ground .
YOU want an accurate hole ? use a Ball endmill and go to one times diameter in depth
Don't have the size you want , use the next smaller ball endmill and make the hole and then use your drill to size, as the drill will not use it's point and be guided by the existing hole and when it reaches the depth you have and want to go farther, the drill will use it's flutes for guidance, not the ground tip
Rich

 

[Richard Hed]

Let me address that particular question exactly and not infringe on Peters explanation.

First --let me say that Ball Endmills are made far more accurate than any drill bit.
Just look at the sharpening equipment used to produce the ball , not only correct diameter but a perfect spherical cutting surface. I have seen brand new factory drills with mishaped configurations
Second-- look at a regular endmill and notice they cut on the outside before the center touches metal _ Why.. because the ourside gives stability to the true center location, in other words, the outside of the flutes render guidance
Third-- Drill bits are Longer than endmills, Right ? well that makes them flexible, which means they drift.
Forth-- But you say, I use a center-drill first ...wrong, (!) center-drills are for making center holes for tailstock live/dead centers and are completely inappropriate for starting holes...why ?------
because they do NOT match drill point center angles 60 versus 118 . If you want to match the drill point, use the appropriate "Starting Drill " ( shorty and matched angles) for more accurate drilling
Fifth-- Starting with a ball mill (no predrilling) means the ball mill is not affected immediately when it touches the surface , which means metal variations/inclusions have no affect and the very face of the ball mill is like a facing operation before the plunge , this means the mass and rigidity of the ball cutter is used to get perfect centering on the workpiece and the amazing thing is as it penetrates the metal , the sides further up the ball , nearer the OD, actually can shift the cutting center to match the true center of the ball endmill.
Sixth-- Ever wonder why drills come in 118 and 135 angles ? it has to do with cutting load and materials , and the 135 is more rigid and which is closer to the ball endmills construction

Hope this helps you and others understand the value of ball endmills
I spent over ten years running a gundrilling operation , drilling up to 48 " deep on stationary 4140 dies which is more difficult than using a gundrill lathe for getting accuracy and we did all kinds of tests and evaluations, and by far , the most accurate and concentric holes were ( started) achieved with Ball endmills, and which sometimes even required the cutters be custom ground .
YOU want an accurate hole ? use a Ball endmill and go to one times diameter in depth
Don't have the size you want , use the next smaller ball endmill and make the hole and then use your drill to size, as the drill will not use it's point and be guided by the existing hole and when it reaches the depth you have and want to go farther, the drill will use it's flutes for guidance, not the ground tip
Rich

Yes, and they are difficult to get too. I only have a couple and they are always inappropriate sizes for what I needs.

 

[Ken I]

Some tips on deep drilling.
Make sure your drill is perfectly sharpened (equal cutting edges).
Use a spotting drill (rather than a centre drill) to start.
Your start must be perfect or you are going to wander.
If the hole is large enough - pre-drill and bore the start.
You can extend drills - as per photo below :-

As awake said - once you exceed the flute length you have to start "pecking" - tedious but do-able.
The above drill used on my 6 Shooter elbow engine to drill a Ø4 x 122m deep hole (that's a huge depth to diameter ratio).
Using a mini-mill and a bunch of tricks.

3 of the 4 holes thus drilled were spot on, the fourth wandered by about 0.1mm which was no problem - but I ascribe that to a slightly less than perfect start.

I have used silver soldered shank extensions to drill stupidly long holes on a lathe - As an apprentice I had to drill a Ø20mm to a blind depth of 1000mm in a Ø40 x 1100mm long stainless bar. (I had two to make).
My first attempt started with a centre drill that ran out slightly (this is the job that taught me how important the start is) - the drill actually came out the side of the bar - I didn't think it possible to drill around a corner like that - I was shocked.
After a tongue lashing and further instruction by my supervising artisan, I pre-drilled and bored the start and all went well - this advice has served me well over the years.

Regards, Ken I

 

[Steamchick]

Excellent advice guys,. Thanks!
I learned about centre drills. I just use them for the small end making a hole just larger than the blunt square end of the real twist drill, so the the cutting edges locate on the outer sharp corner of the hole. The cutting edges - IF correctly and precisely ground - will centre the drill until it gets deep enough to be at size,when the sides of the drill can take over and guide the drill from wandering.
BUT a poorly ground drill, with odd angles or uneven length cutting edges will ALWAYS wander! I have hand re-ground many wandering wonders!
I agree that a rotating workpiece against a fixed drill will cause the drill to self-centre and resist the wandering.
Many suppose twist drills t be stiff, but they are really flexible, twist a tin strip of metal to simulate a twist drill, then compare to a solid bar..... you'll see what I mean.
I am going to buy some ball-end milling cutters now!
K2

 

[Jamie Barton]

Let me address that particular question exactly and not infringe on Peters explanation.

First --let me say that Ball Endmills are made far more accurate than any drill bit.
Just look at the sharpening equipment used to produce the ball , not only correct diameter but a perfect spherical cutting surface. I have seen brand new factory drills with mishaped configurations
Second-- look at a regular endmill and notice they cut on the outside before the center touches metal _ Why.. because the ourside gives stability to the true center location, in other words, the outside of the flutes render guidance
Third-- Drill bits are Longer than endmills, Right ? well that makes them flexible, which means they drift.
Forth-- But you say, I use a center-drill first ...wrong, (!) center-drills are for making center holes for tailstock live/dead centers and are completely inappropriate for starting holes...why ?------
because they do NOT match drill point center angles 60 versus 118 . If you want to match the drill point, use the appropriate "Starting Drill " ( shorty and matched angles) for more accurate drilling
Fifth-- Starting with a ball mill (no predrilling) means the ball mill is not affected immediately when it touches the surface , which means metal variations/inclusions have no affect and the very face of the ball mill is like a facing operation before the plunge , this means the mass and rigidity of the ball cutter is used to get perfect centering on the workpiece and the amazing thing is as it penetrates the metal , the sides further up the ball , nearer the OD, actually can shift the cutting center to match the true center of the ball endmill.
Sixth-- Ever wonder why drills come in 118 and 135 angles ? it has to do with cutting load and materials , and the 135 is more rigid and which is closer to the ball endmills construction

Hope this helps you and others understand the value of ball endmills
I spent over ten years running a gundrilling operation , drilling up to 48 " deep on stationary 4140 dies which is more difficult than using a gundrill lathe for getting accuracy and we did all kinds of tests and evaluations, and by far , the most accurate and concentric holes were ( started) achieved with Ball endmills, and which sometimes even required the cutters be custom ground .
YOU want an accurate hole ? use a Ball endmill and go to one times diameter in depth
Don't have the size you want , use the next smaller ball endmill and make the hole and then use your drill to size, as the drill will not use it's point and be guided by the existing hole and when it reaches the depth you have and want to go farther, the drill will use it's flutes for guidance, not the ground tip
Ric

Let me address that particular question exactly and not infringe on Peters explanation.

First --let me say that Ball Endmills are made far more accurate than any drill bit.
Just look at the sharpening equipment used to produce the ball , not only correct diameter but a perfect spherical cutting surface. I have seen brand new factory drills with mishaped configurations
Second-- look at a regular endmill and notice they cut on the outside before the center touches metal _ Why.. because the ourside gives stability to the true center location, in other words, the outside of the flutes render guidance
Third-- Drill bits are Longer than endmills, Right ? well that makes them flexible, which means they drift.
Forth-- But you say, I use a center-drill first ...wrong, (!) center-drills are for making center holes for tailstock live/dead centers and are completely inappropriate for starting holes...why ?------
because they do NOT match drill point center angles 60 versus 118 . If you want to match the drill point, use the appropriate "Starting Drill " ( shorty and matched angles) for more accurate drilling
Fifth-- Starting with a ball mill (no predrilling) means the ball mill is not affected immediately when it touches the surface , which means metal variations/inclusions have no affect and the very face of the ball mill is like a facing operation before the plunge , this means the mass and rigidity of the ball cutter is used to get perfect centering on the workpiece and the amazing thing is as it penetrates the metal , the sides further up the ball , nearer the OD, actually can shift the cutting center to match the true center of the ball endmill.
Sixth-- Ever wonder why drills come in 118 and 135 angles ? it has to do with cutting load and materials , and the 135 is more rigid and which is closer to the ball endmills construction

Hope this helps you and others understand the value of ball endmills
I spent over ten years running a gundrilling operation , drilling up to 48 " deep on stationary 4140 dies which is more difficult than using a gundrill lathe for getting accuracy and we did all kinds of tests and evaluations, and by far , the most accurate and concentric holes were ( started) achieved with Ball endmills, and which sometimes even required the cutters be custom ground .
YOU want an accurate hole ? use a Ball endmill and go to one times diameter in depth
Don't have the size you want , use the next smaller ball endmill and make the hole and then use your drill to size, as the drill will not use it's point and be guided by the existing hole and when it reaches the depth you have and want to go farther, the drill will use it's flutes for guidance, not the ground tip
Rich

I'm also a fan of using endmills for such purposes, if it works it works. Standard endmills also make great little boring bars to square up or center holes too small to get a proper boring bar in.