Cylinder boring without a cylinder borer.

A while back I had a couple of cylinders for my Aermacchi classic racer which needed reboring. There is nobody in my area who does such work that I know of, so I decided that I would do it myself, but I do not have a cylinder boring machine. The quill movement on my mill is a little too short, so I had to use the lathe. The obvious way would be to spin the barrel and use a fixed tool in the usual lathe manner but there are several good reasons to do the opposite, that is, spin the tool not the cylinder. The first stage was to make a really solid boring bar with easy diameter adjustment. My lathe has a no.5 Morse taper in the spindle which is plenty beefy. I had a length of 51mm 4140 bar of just the right length, so I turned a MT5 taper on one end and threaded the other end to accept a commercial boring head. To ensure rigidity right to the cutting edge I make a solid holder for a carbide insert, which is held into the boring head by two 1/2" pins. The next stage was to make a mounting to support the cylinder rigidly and accurately. This was welded up from pieces of steel from my scrap box and initially machined on the mill with a final truing cut taken with a fly cutter when mounted to the lathe's cross slide to ensure perfect alignment. The hole in the plate to locate the cylinder was also finished in-situ. What is commonly known as a "torque plate" was made to hold the cylinder in place. Now it is ready to go.

Attachment 15501
The bar made to accept the adjustable boring head. I like rigidity when machining. Note MT5 taper on one end and threaded for the boring head on the other.

Attachment 15502 Attachment 15503
Two sides of the boring bar fitted in the lathe and with boring head attached. Note the rigid insert holder in the first pic.

Attachment 15504 Attachment 15505
Firstly using a fly cutter to face off the mounting plate square to the spindle axis. Secondly tramming the mounting fixture after refitting to the lathe.

Attachment 15506Attachment 15507
Cylinder mounted and clamped with a torque plate and then it is ready to do the important bit.

In my experience, few milling machine configurations have the intrinsic accuracy to bore at depth. Main issue is loss of quill support as it descends from the housing, and instances of swivel heads are rarely as square in 2 planes an indicator reads zero.
That can be improved by tramming with quill extended just shy of the stop, with apparatus to swing a larger diameter along X axis; move Y enough to fall within that range. I use a pair of 1-2-3's and 1 2" jo-block as surfaces, switching axis as needed. Wipe the lower surface on inside of wrist to insure cleanliness.
A lathe has all the accuracy built in, mainly as the part rides well aligned Vee's, quite like a jig bore. And a 5MT indicates a substantial machine. Effectively you were line boring. That is 100% possible if the bar is affixed to the tailstock and a center. Carbide tipped are most accurate, a well lubricated steel center is nearly as good. Live centers are often abused, inducing vibration or like harmonics via dry ball cage and races.
Your solution and dissertation are complete with accurate text and well detailed jpeg's. Those cylinders are so short! I'm guessing RPM range is low or mid 'teens? Is that an intake port in pic #4? Two Stroke and another couple thousand RPM?

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Originally Posted by Toolmaker51

Is that an intake port in pic #4? Two Stroke and another couple thousand RPM?

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I am not sure what you are mistaking for an intake port, that is a cylinder barrel, the ports are in the cylinder head. It is a four stroke. Here is a pic. of the top end complete if that helps. The length to be bored is around 200mm.

Attachment 15513

The mystery port now appears to be a DOHC chain-well, seeing side view of the cylinder. In pic 04, the supposed 'port' is peeking out above the torque plate, mounted to fixture proper.
Aermacchi's are triple uncommon in the US; though they supported the small motorcycle ventures of Harley Davidson [under AMF] awhile, in 100 and 350cc. That laydown cylinder is more than distinctive.
Thank's for photo's and clarification.

Ah, now I get it, you mean the pushrod tunnel.
Actually, you are wrong about the 'macchis being so rare in the US. They are actually more plentiful there than here in Europe. HD in the AMF days owned the factory on the beautiful lake Varese in Northern Italy and most production went to the US.
I lived in the US for 3 years (I gave a seminar on motorcycle dynamics to the engineers at Segway and afterwards, completely out of the blue, they offered me the job of Director of Advanced Product Development and got me a 3 year visa so that I could sample the 'mercan dream for a while).
During my time there I collected a whole bunch of 'macchi stuff. Part of the deal with Segway was that when my 3 years was up they would pay shipping costs back to Spain, I had bought a bunch of everyday household items like a mill and lathe and other essential bits and pieces as well as the bike bits, which were all loaded into a container and sent home.

Attachment 15555 Attachment 15556
A view looking away from what was the Aermacchi factory (now MV) toward the lake. Aermacchi started out making sea-planes hence the need to be on the water. It is nice to see that with 2 or 3 changes of factory ownership the Aermacchi jet plane has been kept there. These pix. are from 2014 but little had changed externally from when I was there in 1984. The original slipway into the water is still there.
BTW. Aermacchi comes from Aer macchi which in English is Air machine.

Well, after my errant observations, this developed into a fascinating buffet of history and engineering. My favored diet; since it truly continues to feed me. Your contributions will be stellar Mr. Foale.

Well if you like history here's a little more.
After Aermacchi faded from the scene the factory was used by Cagiva, new guys on the block. Cagiva also faded but the brothers who owned it took on and resurrected the MV marque and made the bikes in the same premises but with modern machinery and manufacturing methods. The brothers got into debt again and recently sold out to HD.
So it has gone full circle. HD during the AMF years owned the factory, then got out and Cagiva used it. that morphed into MV which HD have bought.
Here is a picture from 1984/5 when the factory was Cagiva and another near the same spot when I went back in 2014.

Attachment 15559 Attachment 15560 Attachment 15561

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Quote:

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Originally Posted by DIYer

Thanks tonyfoale! We've added your Carbide Insert Holder to our Machining category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

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I note that you have added my post into 3 categories. I didn't know that happened.
At the time of making that post I couldn't find the pix. that went into more detail on the boring bar and tip holder. Since then I have found the pix and I intend to make a separate post with more detail on those items.

I've been thinking of boring in the lathe for a while but using a bar between centers as I have much smaller lathe. I used to have access to boring bars and did a lot of 'conversions (800cc Yamaha XS650, 378cc Honda CB360, plus 'stock' kits) I hadn't thought of welding up an 'angle plate' although I had expected to face it with a flycutter. (I'll probably make something from an old automotive brake rotor, they run true and are decent quality cast iron)
HD has something of a history acquiring companies, particularly if they want a specific piece of patented technology.
When I was teaching at MMI I did a little research on the HD/Aermacchi, HD bought Aermacchi in 1961 when the 250/350 were still competitive race motors.
BTW Tony,I've read a lot of your motorcycle stuff over the years, were you involved with the Suzuki 'NUDA' concept bike? It has similar steering set up to the GSX you built (pictures at Cadwell Park)

Quote:

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Originally Posted by crazypj

I've been thinking of boring in the lathe for a while but using a bar between centers

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Between centres is fine, the only problem is making an easily and accurately adjustable tool. It the lathe is solid enough then the way I did it allows the use of a store bought boring head with fine adjustment. Both ways work OK.

Quote:

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Originally Posted by crazypj

BTW Tony,I've read a lot of your motorcycle stuff over the years, were you involved with the Suzuki 'NUDA' concept bike? It has similar steering set up to the GSX you built (pictures at Cadwell Park)

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Maybe you are thinking of the Rusty Falcon which predated the Nuda. The Nuda had conventionally orientated handlebars whereas the Falcon had roughly vertical bars as did the QL and Q2 series of bikes that I built, the first versions predated both of Suzuki's concept bikes. I had nothing to do with of those. Both the Suzukis had FFEs (Funny Front Ends) as did those of mine which you mentioned. However, the mechanisms were quite different to mine.
For those unfamiliar with these concept bikes here are a picture of each

Attachment 15633 Attachment 15634

Here are more. showing a test bike converted to my FFE and upright handlebars from around 1980.

Attachment 15636 Attachment 15637

Attachment 15635

When talking about funny front ends the idea of hub steering on a motorcycle dates a long ways back
I had one called a ner-a-car
Ok this is a boringly crazy old bike I had one given to me that was little more than a rusted frame. Through the years I restored it to almost new but let it get away from me.
Here is a video of one nearly like mine except mine was a 1923 American made with the smaller 2 cycle engine
https://www.youtube.com/watch?v=noZ6gfcnP8c

This video shows the steering better and is a lot closer to how mine looked when it got away.
https://www.youtube.com/watch?v=XS6LHXRVzzs

Yep, it was the Falcon I was thinking of. I know I downloaded a picture of a GSX (maybe GSX-R?) engined special a few years ago (probably 12+?) If it isn't one of yours I'm wondering who built it? It had 'vertical' bars similar to the BM

Quote:

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Originally Posted by crazypj

Yep, it was the Falcon I was thinking of. I know I downloaded a picture of a GSX (maybe GSX-R?) engined special a few years ago (probably 12+?) If it isn't one of yours I'm wondering who built it? It had 'vertical' bars similar to the BM

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That sounds like one of the Q2s that I built. I did post a photo of one here in another recent post but here are some different pix. of both a QL and a Q2.

Attachment 15645 Attachment 15646

I am familiar with the Ner-a-car and I had pictures in my chassis design book.

Attachment 15647

THE ISSUE WITH THIS TYPE OF BORING IS CENTERING UP RIGHT/ACCURATELY..and square. from end to end.yes it can be done, but be sure to get it square from end , to end. also it should be bored .004~.0055 smaller than the finish size for cast materials like cylinders on engines. the cast is not realy cut well but rather cht&broken out leaving fishers about .002~.003 deep, ( depending on the amount of material being taken out per pass, rigidity set up and type and sharpness and shape of the cutter. the cutting edge is usualy about .020~.025 wide, angled of corase.If i was using a carbide incert i would go for a incert with a raidi, dont use a sharp point that will tear the material deeper and effup the cylinder and possiably pull the cutter into the bore. on a std boring bor used for engine block boring the chtter is sharpened after every block done...well it should be, doing it that way the cutter will cutt better, less heat, less chatter, better hole, less stress and the cutter will last longer....yes last longer if you sharpen them more often,other wize when your burning up the cutter and then go to sharpen it you end up taking a lot more material off the cutter shortining it's life and the sharpening diamonds. I see no issue using a bridge port boring unless yours is all wore out, there not a lot different than a boring bar, boring bar has a small er quill but bearings are spread appart farther but the quill does go a lot farther than a bridge port type mill. and if you know how to use a mill correctly you know that you can use the knee for the Z not the quill and that keeps the quill supported way better., but many people dont seem to know what the movable knee is for. be sure to adjust the ways/gibs if you havent.you can also check it with dial indacator from locked to non locked possition, it should be less than a thou....if not ADJUST IT!!!!! Ive seen lathes with way more movement in the carrage,cross slide/compound than a mill has., and yes Ive seen wore out mills too.. as for the spring return hone & hand hone...... if you bore the correct amount then try to hand hone...your wore out . and cheep hones are ****. use a good hone with the propper stones( usualy 3-4 grades of stones for every hone job to get it right).torqueplates are also mandatory for most engines if you want them right. I have boring heads I use in my mill,never thought about sticking one in my lathe...I do like the idea especialy for wonkey shaped thin stuff that is hard to put in the lather and spin it along with boring bar chatter that can creep up and bite you that a boring head with right incert in it. Ive seen that addaptor for the boring head to use a incert,I was gonna make one, or just but the boring head that takes the insert..$64 on flebay, addaptor....about the same.go figure. I only have 2 3" bridgeport boring heads so i was thinking on getting some smaller ones...

Quote:

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Originally Posted by marksbug

THE ISSUE WITH THIS TYPE OF BORING IS CENTERING UP RIGHT/ACCURATELY..and square. from end to end.yes it can be done, but be sure to get it square from end , to end.

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Square end to end is not the way. That relies on the bore being true to start with. I set it square to the mounting flange and align it as shown.

if your sure your jig is straight&true.but I would check it. if it's out a few tenths one one end....and it's 7" long...it's out quite a bit at the other end.yes set it up from the machined end and go from there. but check to be sure your jig is true every time. std practice is use a file to make sure there are no puled up threads or any thing else , burr, bump,gasket material/sealer what ever that will throw it off on the jig. no not all bores are where they are supposed to be, we use a BHJ bore true for many engines so you could put the bore where it was supposed to be. some engines the deck surface is AFU from the factory and needs to be trued.if you were top use that you would be boring the cylinders at the rong angles and much bigger. some oe engines were around .020" out from end to end and up to .010 side to side. boring of something that far off is disaster. all of the mopar 340 blocks were out .016~.020, Ive done a lot of those and every one is about the same, witch dosent make good sence since it's about the same engine as the 273,318&360 witch are usualy withen about .008 witch is about the same as other american v8 engines. the 340 must of had a spcific machining center diferent than the other small block mopars for the roughly 5 years it was in production., chevy blocks have waves on the decks of most, ford can go either way. inline engines are usualy withen about.006.end to end and side to side.very few if any are dead on.

We had a ford inline 300 I wanted to rebuild for a guy's rat rod, the shop I used since I didn't have the equipment to do it my self. had to shave .008" off the deck #2&#3 bores were .010" off center in the opposite directions Took a while to figure that one out the only thing we could determine was the engine had previously bored to .030" Ordinarily the block would have been scrap in my book but the guy wanted to go max overbore and a 4.375" stroker crank I think he wound up with somewhere in the neighborhood of 336 to 338 CI range Not a high rev'er but had torque for days

the MT5 boring bar is snugged in with a draw bar?

This thread is of special interest to me. I joined this list initially as I was, still am, in the process of rebuilding an obsolete jet ski engine. It has been pushed aside many times due to other, more pressing issues, but I am always on the look out for ideas to help me complete the project. As you mention Tony, there is no one around here that wants to mess with boring this engine. So I am going do it myself. I have thought about and discussed here on a couple of threads about just honing it to size. But I think I am going to have to re-sleeve the cylinder, so the honing is not really a very good idea. The engine is a 2 cylinder 2 cycle. Both cylinders are in the same jug, so spinning the jug on my lathe is not possible. Bore and stroke are 83 mm x 71mm.

I am wondering if my lathe is up to the task of doing this in similar fashion? I have an 11" Powermatic/Logan. I am wondering about the stiffness of my spindle. The spindle is smaller than most 11" lathes. The through hole is just large enough to get 1" round stock through it if there are no chips in it. The taper is some proprietary thing in the range of #4 morse, but the taper does not match and it is about 1/2 the length of a standard Morse taper. The spindle nose is 1 1/2 x 8 thread. I am sure the internal taper not up to the task.

I am wondering, assuming that I have the skills to actually make the adapter, do you think the spindle is stout enough to attempt to make a similar boring set up using the external threaded part of the spindle nose? Possible I can make the set up stiffer, using the tail stock as Toolmaker mentioned?

Thanks for your input.

John

Quote:

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Originally Posted by hemmjo

I am wondering about the stiffness of my spindle.
John

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preface: I have no idea what I'm talking about

If your spindle really is of suspect stiffness, can't you just bore the cylinders by sneaking up on the target diameter with light cuts?

Do you have a steady rest?

how would one measure deflection of, eg 1" round rod in the chuck, deflection at the point where the cutting tool would be?

Quote:

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Originally Posted by satx

the MT5 boring bar is snugged in with a draw bar?

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yes, of course.

Quote:

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Originally Posted by hemmjo

I am wondering if my lathe is up to the task of doing this in similar fashion? .......I am sure the internal taper not up to the task.

...... do you think the spindle is stout enough to attempt to make a similar boring set up using the external threaded part of the spindle nose? Possible I can make the set up stiffer, using the tail stock as Toolmaker mentioned?

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John,
I think that you are pushing the envelope with a lathe of that size. Apart from the rigidity of the spindle, is your cross-slide large and stiff enough to mount the cylinder block on? Although back in a previous life I did similar jobs on a Myford 7.
As I was reading your post, I was going to suggest using the threaded nose as the support but you were already there as shown in your last paragraph. Even with that I think that you would still need to use the tail stock with a centre for added support. That means that you need to incorporate another method for adjusting the depth of cut.
Good luck with it, to do a good job it will take a lot of time, patience and care with that lathe, but that is no reason not to try.

I'll have to edit more material in evening; but this is a perfect example of building up tooling to accomplish a specific task. The order is sort of important, but not critical, just logical.
This also answers ralphxyz thinking #3MT too small. Use the spindle threads.
a] an indicating setup to measure odd spindle taper. There a few; Morse, Jarno, Brown & Sharpe and a sh_ _load of proprietor specials. Who cares, we're making our own!
b] offset center to produce it on what will become a boring bar
or
a] establish dimensions of thread
b] procure means to cut ID thread what will become a boring bar.
c] plate fixturing cylinder block in 3 correct planes; even without enough cross travel. Knowing accurate distance between centers needed here. Prepare torque plate at same time.
d] boring bar with that spindle taper or thread and center drilled opposite end. It'll need means of adjustment. We'll get to that.
e] known piston diameters minus hone allowance and correct measuring instrument.

Of the two, considering a small lathe, choice of threaded will allow a size without a small neck joining a decent size bar diameter. Center drill the end for tailstock support. A center may be a little bearing diameter but is sort of zero clearance for endplay. Slow RPM and a decent feedrate can be experimental dialing things in. Order pistons afterward, unless you blow the whole thing, if you buy .010's and miss you are stuck without replacement sleeves.

Poster 'marksbug' offered good details on boring, especially cutting .004 under and bring diameter in by hone, to stop fissures in cast iron. #28 @ http://www.homemadetools.net/forum/c...-borer-55286-3

A suspended boring bar [line boring] is worth the extra preparation and building. Instead of attaining precise diameter control with an offset boring head, find or make a boring cartridge. Visualize a threaded boring bit crossway in a threaded bar. They have a re-usable dial with graduations for size control...time spent in tapering the bar itself could eliminate that as a source of harmonics that create chatter, lots of way lube [as in WET] and high speed tool bit...My bet; this is completely achievable.
Attachment 25588
I expect and hope a lot of other readers will ring in. It's why we're here, after all.
And hemmjo/ John "I am wondering, assuming that I have the skills to actually make ___________". Develop skills by using them. Some volume of readers here, use ability to interpret and visualize as the keystone of skill. It takes some confidence, sure; but understanding is a better foundation for confidence than diving in blind. Not far away in comparison to connect the dots.
It also means you'll pick up on what needs attention to get improved results, by the time you get 'to size' you'll be gung-ho for next opportunity.
You'll want good ID measuring tools. On stuff like this I often use two different methods of confirmation. Cheap insurance.

Limited cross travel......that's a problem. Not big as insufficient center height! Determine the exact distance and plan a subplate doweled for each bore. 4 capscrews one each corner, 2 dowels diagonally opposed near a corresponding screw. The sketch will make this clear, not to size not to scale.

I too have a jet ski engine that has been shoved to the side( 500 wave runner) I did all the machine work long ago including boring&decking and mild port work,I did it all over 25 years ago...I threw away the ski 2 years ago after cutting it up with saw... yes you can bore it on the lathe if you set it up right.you need to leave about .004-.005" smaller then finished size for honing.some bore to size and them do a light hone, that does not last.also kills the engine, boring the cast liners fractures the iron about .004 deep and the pieces come off when running, thus the hone of min .004 is required to do it right. and dont forget to deburr ports after honing so the rings dont gram them... I guess I need to get rid of this yamaha 500 engine in a box Ill never need it and the kids are grown&gone.(as is the ski body). I did it on the same rottler boring machine as I did 632+ci promod race engines,offshore race engines and everything else.( including my 4 wheeler and yz 250 dirt bike) and honed on our sunnen ck 10 hone machine.decked on the strom vulcan 85b. if it chatters you may need to bore less and hone more...(after trying everything you can to stop the chatter.(speed, setup, bar size,even big rubber bands around the chuck&cylinder to try to keep chatter away....yes it can work. if you have a chip tray be sure to try to keep it from vibrating adding weight or what ever. many times chatter is a harmonic set up by something else on the machine reverbrating a small amount into a large amount of hair pulling chatter.(thus the humongus heavy securly mounted lathes instead of small portable lathes doing production work...

Now that is a substantial boring bar, I want one but #mt is my largest spindle.

Ralph

also in the big skeem of things, many bores are nowhere neer where they are supposed to be....so if your boring a cylinder .030 and get it to bore the entire way down you have done about as good as many manufactures..... not saying get it good enough, but if you have to get it this way or that way, get it so the piston go's straight alined with the rod&crank.the pin will pivot it the other way without any issue. yes it does alter cam&ignition timing, but getting it done when there is no other way....it's better than walking ... we had BHJ bore true to use on big block gm race motors....some were way off.thats why they make the bore true so you can put it right. I have had to offset bore a wore out block so it would clear the max bore. no isues, but not a race motor either.

I always like seeing your solutions, getting around obstacles. Very nice work.

If jet ski is a two-stroke you'll need some special guided honing stones to bridge ports. Last time I had to buy some for Sunnen hone they were about $60.00 pair (around 2005) Of course, you need the holder and drive mech but there are a few aftermarket companies making Sunnen copies nowadays which are very affordable. Don't get AMMCO, they are expensive for various parts and not easily available (guess what I've got :( ) AMMCO does have a slight advantage if your doing four-stroke motors, you can fit 4 stones so grinding goes twice as fast. Max rpm for hone is around 400rpm, The 3 leg 'glaze busters' are worthless for actual cylinder honing (they follow whatever contours you already have) A ridgid hone will allow cylinder to be honed to within 0.0001" (but 0.0003"~0.0005" is more usual. (using a low rpm hand drill and bore gauge) You can correct taper quite easily (as long as it's not too bad and any out of round you can feel as drill will 'catch. Just start at the tight spot every time and measure in multiple directions

I didnt have any issues with jet skis or other 2 strokes,I did always port&deburr the ports before honing to get rid of any sharpe edges for the stone'sor guides to catch on. and remember you dont have to spin the cylinder, mount it fixed and spin the boring bar like boreing machines do. you should use a real boring head so you know how much your sneeking up on the size( witch should be about .003~.005" under the finished honed size ( hone a min of .003, a hone of .005" is best and will last longer....if it all go's right.
some small cylinders are a bitch to keep the taper out of due to flex on the non supported portion of the cylinder (of the types that have a non supported end hanging out that go's down in to the case) some are kinda thin some are thick, you deal with that as it comes. I always did mine on a sunnen ck 10 hone,I nolonger have that, I have 3 different sunnen hones now, I havent dont any small stuff other than tuch up my vw aftermarket big bore cylinders that were NOS and rat piss pitted...badly. and not the hone profile I wanted. and now at over 80000 miles...they are still sealing like the first week I put it together( witch is very good). still with big divits/pits from the rat pis, all positioned upward so not to collect any thing and use total seal piston rings witch Ive used a few hundred set of.and I recommend for all engines. the key to sealing and lasting is the hone profile, good rings, proper clearance and a GOOD AIR FILTER!!! I also ceramic coat all my piston tops and DFL coat the piston skirts&pin bores.

It generally depends how big the exhaust ports are, some will 'swallow' half of hone :D

Ive never seen any that would do that, the mercury long finger ports were a pain thats for sure. and if you didn not set all the guides just right that can cause issues on any ported cylinder. I may of alos been using longer guides,I did many times change the location of the stones to gain some clearance in the bottom webbing of some cases.