Boring Bar

[jsmith]

What are peoples opinions on boring bars, particularly Van Norman portable one's.

I've got a lot of engines needing rebore's at the moment and was considering buying a machine and diy'ing it. I've not done rebore's before but I'm a fully skilled general machinist.

What are the pro's and con's of this type of machine? Should I not bother and keep contracting out? Are these machines accurate? Are they hard to use? What do I need to look out for?

Cheers Guys...

[Greg]

Theres no problem at all with the van norman bars, I had one until I bought an overhead boring machine and used it almost every day. With a sharp tool they are dead accurate. You just have to make sure the top of your block is flat before you bolt it down or it will bore perdindicular to whatever the deck is. I used to deck my blocks first, then bore them. You can also o-ring blocks using one of these bars.

I leave .005" to hone out but apparently you can get away with as little as .002". I made up a honing machine using a Sunnen style friction feed honing head so it isn't a big job to hone this much out. If you want some photos of the honing machine to get some ideas let me know.

[jim fuchs]

would you post some pic of the honi ing machine .thanks jim

[Greg]

Jim, heres a couple of photots I found. I'll take some more detailed ones in the next few days and post them up.

It uses a 1hp 3 phase 415v motor through some reduction pulleys and an over centre idler to engage the spindle. The head winds across using a timing chain connected to the handwheel on the front. The rollover table the block sits on tilts to 60 & 90degrees for V style blocks. The bottom of the cabinet is the oil reservoir and holds around 120 litres of honing oil with a pump mounted at the rear. It's hand stroking at the moment though it's set up to use a hydraulic ram to stroke it. I'll fit it once the right size ram and a hydraulic powerpack come up at the right price.

It's no problem to hone .020" from a V8 block in 2 hours or so. I use it for all the single cylinders I do as it's quicker than setting the up to bore them first. It'll hone accurately to .0001" to .0002".

I made up torque plates for most of the common engines I do which are very worthwhile.

[hollywood63]

just a test I can't seem to reply to anything????

[RRBD]

GREG, HOW ABOUT POSTING SOME ROUGH SKETCHES OF YOUR HONING MACHINE, IT SOUNDS INTERESTING. I HAVE BEEN WANTING ONE FOR A WHILE, BUT CANT JUSTIFY THE $$$

SCOTT

[proto]

test

[MikeyFIN]

Test..and Greg yes sketches and how did you do it?

Been on the lookout for a boring bar and a hone quite a time now.

[bruce]

Doing some forum cleanup and I moved this post over to the Shop Equipment forum.

The Hone looks like an interesting project got me thinking about making a small one for doing my blocks. Probably got most of all the major components sitting around in the shop. I do my blocks now with the old hand method using a big hand drill and my Ammco Hone. From the looks of Greg's setup its just a matter of mounting the hone to a spindle with a motor to drive it and a pivot point. Well that would be putting it in simplistic terms, there is a little more to it than that I am sure. Just need to come up with a plan on what works and what won't work.

Any thoughts anyone?

[84-1074663779]

I have the last mortal remains of an old power hacksaw here and it has a coolant pump and sump too. Now if I were to get an old junk drill press from somewhere that had sufficient stroke, it might be possible to bolt the column of the drill press onto the flat bed of the hacksaw, and use the con rod to make the drill spindle go up and down. The speed and travel would be just about right for a hone.

I can imagine something like James Watt's beam engine, with a vertical con rod at one end of a horizontal rocking beam, and the drill spindle at the other going up and down.

It would then be fairly easy to adjust the spindle speed to get the desired cross hatch angle.

I will probably never do this, but it might give someone else the beginnings of an idea.

[Greg]

Guys, sorry, I will take some more photos and post them up. Tony, I tried a few different things to stroke the hone but anything crank driven isn't the best unless you can disengage it easily as it gives you no oportunity to dwell in one spot, the sunnen CK series hones do use a mechanical setup but it has the facility to hit a button and dwell at the bottom of the bore for an extra turn. I still can get a straighter bore on this machine than on the CK10 that I used to use. What I will use one of these days is a hydraulic power pack & cylinder and set it up for variable speed and also the ability to dwell wherever the cylinder is tight.

At the moment, I stroke it by hand and it isn't too hard work. The basic setup is fairly simple. The box at the top has a 1hp 1400rpm or so 440v 3 phase motor which runs a v-belt to a centre idler and a belt from the idler to the spindle. Both sets of pulleys are around 3.5:1 so the spindle speed ends up at 80rpm. The belt from the idler to the spindle is tensioned by an over centre idler that locks in place once it engages the spindle. It is activated by a handle on the side of the head of the machine. The spindle bearing is an old renault wheel hub with the v-belt pulley mounted on top.
I modified the original driveshaft spline so I could bolt up a toyota diff flange and uni joint which drives down to the honing head. The honing head has a uni joint built into it which works for the bottom end. I used a friction feed head made in Melbourne, Au which uses Sunnen stones etc.. you could quite easily use any Sunned AN style hone head which you can pick up off ebay for $100 or so. The friction wheel is nice though to adjust the load without stopping the spindle.

The head pivots on a fulcrum that slides from side to side along 2 bars, it is wound from cylinder to cylinder using an SR timing chain and two gears, connected to a handwheel at the front of the machine, kind of like the steering setup on an outboard boat.

The block sits on a cradle that can tilt 30 and 45 degrees in each direction to hone 60 and 90 degree engines and the block is held down either by a bar through the main tunnels or a jig that bolts down on top of the block. There is an oil pump mounted in the back of the machine that picks up from the oil tank which is the bottom 4" of the cabinet which holds around 100 litres of honing oil.

If anyone has a question or wants a photo of any particular part just let me know.

[bruce]

Greg, Could you take some side shots of the head assembly? Sounds like your machine is built from salvaged parts from the scrapyard. I guess a CV joint and the shaft out of the trans would work for the top bearing/joint setup, mate the axle up to my Ammco hone I now use by hand build the framework to house it all. I have a variable pulley setup off an old Sear Lawn tractor I could use for a variable spindle speed. I only do single cylinder engines so it would not have to be as big in size. Could an air cylinder be used to stroke the head?

Sounds like a new project to work on . . .

[Greg]

Bruce, heres some photos, i took a few so they might take a bit to load. You might be able to use an air cylinder, the only problem would be that it takes more force to push the hone head up than it does down, but a gas strut or spring to overcome gravity would probably do the job there.
You could set it up using a two way dcv switched by adjustable stops on a rod that moves up and down with the head of the machine. You might also be able to use an adjustable flow control valve to even up the up and down stroke and another to control the stroking speed, thats what I plan to do one day with hydraulics. You also need to sort a way to move the honing head in and out of the bore, I'm thinking of an over centre pivot arm to mount the actuator on, so you just lift a lever and the whole head moves up without having to readjust the stops on each cylinder. I have seen some hones that have a telescopic spindle that can be slid up and down and locked at both top and bottom. Theres heaps of different ways to do it, just depends what you have available to make what you need.
Saying all that, I've used this machine by hand for almost 5 years and do almost all single cylinders that I do in it as it's quicker than setting them up to bore for up to .040" or so. Using AN100 stones it removes around .001" per 10 strokes so you can really rip the metal out.