Van norman boring bar - struggles around 20 thou cut?

[Savedbygrace77]

Hi everyone and a good morning to you all!

I use a van norman boring bar 900 ALOT, fantastic machine, cuts to well within 3 tenths if not dead on. Anyway - i have noticed around 20-30 thou the finish starts tapering off a bit (now look if you havent seen the finish on a van norman yet you will understand!! its near mirror like!), meaning I have to run 2 cuts for a 30 over - so trying to do it in one cut. The finish is so superb that I just ball hone the surface down about 1/2 thou, plus I keep my bits in shape and im pretty certain the machine is in the slow position (seller mentioned there are 2 speeds but ive never verified??), sbc cylinder takes about 45s top to bottom iirc but I might VERY well be wrong. might be 1min -

Surely these machines should manage a 30 thou cut in one pass on a std chevy block correct?

Could it be a worn motor? I can try and take some amp readings with my klein clamp tool after 4 holes when she warms up a tiny bit and see if its high for the motor rating-

Any other thoughts/ideas? I could prob remove the motor and turn the armature on lathe and pop in new high quality brushes too - would that restore the power/torque to the motor?

 

[Savedbygrace77]

Maybe im just overthinking it and should run the 30 cut and hone but id like the machine to perform as well at 30 as it does at 18-20 (my usual first cut for 30 over, i do the remaining last pass)

 

[Dan from Oakland]

You are free to do as you wish, but honing .0005 with a ball hone is not going to remove the fractured material left from the boring operation, nor will it provide a proper crosshatch needed for the rings to seat. The bored finish may look great to the naked eye, but under magnification it certainly will look like a phonograph record. Regarding the depth of cut issue, .030 is .015 on a side and about as much as I would push the bar, but I would certainly leave about .003" for a finish pass. Van Normans are all gear drive from the motor to the spindle, so nothing is slipping. All the motors I've seen on these bars are repulsion/induction not commutated AC motors, so I doubt your motor has any brushes in it unless its a very old bar.

 

[Garwood]

Dingle honing a bored hole is missing some fundamental concepts about how honing and rings work.

You need a rigid hone. With the right stones.

Learned much about honing recently and around 5 thou on diameter is a good amount to leave for honing if you have a nice bored finish. Coarse stones will take the peaks off in a few swipes.

 

[Servicar rider]

I use two of these old boring bars (a 777s & 944s) and have for years. Good machines! I never push mine over about ..040 as a maximum cut though.. The bigger the bore the more power it takes ? A rottler will take a .100 cut and hold size. I don't like honing much as you other guys and I usually leave about .0015 to finish hone with a good sunnen ridgid hone. About 3/4 of a thou is how deep the threads are from boring and the hone will quit singing at you when the threads disappear and a few more swipes and you're done. Throw the ball hone away they are worthless. Dan is right about the motors.

 

[Savedbygrace77]

Thanks - well ive done about 50 motors since i got the norman and they are running great.. I do have a ridgid lisle hone that i have used, i cant say for sure how much I take off or not, the ball hones are very nice for my application, havent had an issue -

either way back to the bar, thanks for the info regarding the motor.. ill see if i can see how many amps it draws.

So could I service or have the repulsion/induction type serviced, do they wear down?

Thanks

Here is the machine/motor - can anyone ID it? Model is a 900-



Found this - is this what it looks like?

 

[Servicar rider]

Mine acts about the same regardless of the size of cut. Those motors don't get weak from age although I guess one could wear out? Are you sure your tools are correctly sharpened? are you using the original style brazed carbide cutters or the Lacey Williams replaceable insert cutters? A dull cutter or one lapped wrong with the wrong angles takes alot more power to run? Maybe that's your problem. Once again, throw that POS ball hone away, you have been lucky so far that your rings have seated in those 50 engines.

 

[gappmast]

I use two of these old boring bars (a 777s & 944s) and have for years. Good machines! I never push mine over about ..040 as a maximum cut though.. The bigger the bore the more power it takes ? A rottler will take a .100 cut and hold size. I don't like honing much as you other guys and I usually leave about .0015 to finish hone with a good sunnen ridgid hone. About 3/4 of a thou is how deep the threads are from boring and the hone will quit singing at you when the threads disappear and a few more swipes and you're done. Throw the ball hone away they are worthless. Dan is right about the motors.

 

[gappmast]

.0015" is a little light for honing. The industry standard is .003" to .005" on diameter. I know if you hone .0015" the cylinder will look great, but the fractured metal from boring is still there. Put a bore scope in a spark plug hole after 200 miles and you will see the fractured metal

 

[Dan from Oakland]

One thing just noticed in your posted picture above- that yellow extension cord- what wire gauge is it? Looks to be a cheapo 16 ga cord. If so, that's a bit on the light side for running an electric motor of anything over about 1/4 HP. Probably not gong to solve your power issue but................

 

[moonlight machine]

Thanks - well ive done about 50 motors since i got the norman and they are running great.. I do have a ridgid lisle hone that i have used, i cant say for sure how much I take off or not, the ball hones are very nice for my application, havent had an issue -

either way back to the bar, thanks for the info regarding the motor.. ill see if i can see how many amps it draws.

So could I service or have the repulsion/induction type serviced, do they wear down?

Thanks

Here is the machine/motor - can anyone ID it? Model is a 900-

View attachment 381796

Found this - is this what it looks like?

Is the Lisle hone the one that has 3 stones and has spring loaded wimpy ass legs holding the stones against the cylinder walls? If so it is a POS and belongs in the bin with the bally hone. get a rigid Sunnen. No real engine shop will use that junk.

 

[mastuart]

What are you using to measure your bores with? Make me wonder when you said you had the lisle but not sure what you took out with it. As far as the bar power. Shop I used to work in had 3 or 4 Van Norman bars. I dont remember how the number system works. We liked to use the small bar to do 4 inch or smaller bores 30 over or less. Of corse if it was to be 30 over we would take 25-26 out and leave 4-5 to hone. If we were doing a 400 chevy (bigger bore)we would use one of the bigger bars. The smaller bar seamed to be down on power to do the bigger bore in one pass. If your bar can bore a sbc cylinder in 45 seconds to one minute it must be a super duper one. Must spin real fast. Does anyone know if any of the older Van Norman bars were 2 speed? My kwik Way is a 2 speed .

 

[Servicar rider]

My 777s is a two speed. They made a 777s4 that is a 4 speed, but very rare. I have only ever seen one. The s4 was for boring steel sleeves according to the operators manual.

 

[mastuart]

Is the 777 a bigger bar than a 944?

 

[Servicar rider]

Yes

 

[Servicar rider]

.0015" is a little light for honing. The industry standard is .003" to .005" on diameter. I know if you hone .0015" the cylinder will look great, but the fractured metal from boring is still there. Put a bore scope in a spark plug hole after 200 miles and you will see the fractured metal

I've taken motors apart I've bored and never seen any issues, nothing but the usual honing traces. Like I said you can hear the sound change when the hone gets past the fractured metal. I know other guys like to leave more to hone or can't bore to a size so they get close and hone it to size. I just don't see any reason to have to hone that much? Do whatever works for you.

 

[Savedbygrace77]

Thanks for the info.. and despite all the advice I'll keep using my lisle hone and flex hone from brush research. Fyi the lisle hone is a serious hone, adjustable with 2 stones and 2 wipers..

As for performance I would like to look at the power issues.. the bits are original and I keep them in shape on the stone. The mirror finish alone is testimony to the quality of the cut.

Does anyone know if mine has 2 speeds? Sleeve a 454 with it once and thttook a bunch of 20 thou cuts.. I'll try again without a wimpy cord and see if that had anything to do with it. I have some blocks I have to bore pretty soon..

I did buy an indexable tip from Goodson I'm going to try. I test milled a 1/4 inch bit holder from a stainless bolt, but wd like some recommendations on what steel I can buy that will be easy to diy flame harden once I'm done threading etc..

 

[Limy Sami]

Thanks for the info.. and despite all the advice I'll keep using my lisle hone and flex hone from brush research. Fyi the lisle hone is a serious hone, adjustable with 2 stones and 2 wipers..

As for performance I would like to look at the power issues.. the bits are original and I keep them in shape on the stone. The mirror finish alone is testimony to the quality of the cut.

Does anyone know if mine has 2 speeds? Sleeve a 454 with it once and thttook a bunch of 20 thou cuts.. I'll try again without a wimpy cord and see if that had anything to do with it. I have some blocks I have to bore pretty soon..

I did buy an indexable tip from Goodson I'm going to try. I test milled a 1/4 inch bit holder from a stainless bolt, but wd like some recommendations on what steel I can buy that will be easy to diy flame harden once I'm done threading etc..

Probably no need to tell you, but for general info - when switching to the indexible tip be careful setting the dia, because IM (ltd) E they don't always cut the same dia as the brazed tip cutters.

 

[slowmotion]

Agree with what Sami said about different cut diameter with insert style cutter/holder, it will not be on the same center so you'll have to adjust your setting mic. And you will not get away with dingle honing a half thou with them either (I can't believe you do now actually), the finish will no longer be as smooth. I bored with one for years and the OE cutter does give a very smooth cut. That bar should easily cut .050", that's what I used to do when sleeving. Eventually I had to have the motor rewound by a reputable elec shop as it lost power.

 

[Savedbygrace77]

hi thanks - ill test a block i have to sleeve first.. well the cutter tip is in a straight line, nothing offset, but ill keep an eye on that thanks. Yes was considering rewiring motor at some point. even a 30 thou i do in 2 passes cos the finish tapers off after 20 thou.. i usually leave 1 thou for honing, i meant 1/2 on each side my bad.. bored my 383 stroker and its running excellently, either way to each their own.. all my engines run incredibly well, ive never had a single issue with ring seal fwiw.. i have on occasion run a BBC hone in the sbc bore as well, i must be annoying many folks here but it is how it is..

Im still curious what steel I will be able to use in my hi torque mini mill that i can heat treat with a torch and oil dip to add some strength for what i need...?

I am using the original VN holder, just the tip sticking out was i believe HSS and its worn down-