I bought a band-knife splitter

[Matt S]

In this episode: Matt plays around with dangerous electrics. Best not to copy me if you're not familiar and comfortable with the risks.

As noted earlier the control panel got damaged in the move. The 60 year old plastic had the structural strength of vintage cheddar so I built a replacement. Bit of an awkward setup but luckily there was plenty of space in the casting for a choc block to extend the original wires.

 

This machine is built to run on 3-phase electricity. Same voltage and frequency of angry pixies as normally come out of the wall sockets in my country but each 120 degrees out of phase with the previous. This allows a smoother supply, especially for higher-consumption appliances. The splitter is only rated to consume 1100W so I presume that it's purely because 3-phase motors are simpler and more reliable than single-phase, and this machine was designed for use in a factory. What idiot would try to run one in a small workshop eh?

Unfortunately I don't have 3-phase laid on so I had to make other arrangements. Upgrading to 3-phase supply would cost about as much as a brand new machine. Replacing the 4x motors with single-phase ones would cost £400, even if I could find cheap drop-in replacements. VFDs would require one per motor, connected directly, with the switchgear rebuilt -- not cheap and I wanted to keep the switchgear as original as I could. Cheap 3-phase petrol generators are minimum £350, noisy, and of questionable quality. So I needed some sort of phase converter.

After some study on the subject I decided a rotary converter would be better. Prices were not attractive so I built one out of £150 of parts.

Then I toasted the idler motor in my converter. Whoops.

[Matt S]

Long story short I went back to the KISS approach: a Steinmetz arrangement (static converter) on the largest motor on the machine. Cheap, simple, imperfect but adequate. What I should have done all along. 

She lives.

 

A little fiddling with balancing capacitors later and I've got it about as sweet as it's going to get. The machine at idle consumes less power than my previous converter did alone. (Temporary control panel installed in spare space under my clicker press -- which means it'll be there permanently.)

Time to tidy up the electrics and put he machine back together. I bloody hope this is going to be worth the trouble...

[bermudahwin]

Looking good, Matt, keen to see the results when its splitting.

Well perservered

H

[Matt S]

With the electrics mostly functional it's time to get the mechanical arrangements sorted. All the pieces went back together without too much trouble and I could revel in its yellow formica beauty.

Then I had to put the blade in, which required me to remove the upper blade guide. And I was not pleased with what I found.

First a little background. A basic/classic band-knife splitter like mine is not the most complicated machine in the world. Essentially it's a two-wheel bandsaw turned on its side with motorised feed, a motorised blade grinder/sharpener and a dust extractor. However what it is is incredibly accurate and rigid. It has to because we're talking about a machine intended for reliably splitting materials with a variance of a fraction of a millimetre. The blade, just 0.4mm thick, is kept dead flat during the 12" length of the cut by a pair of blade guides, very flat and smooth steel plates which sandwich it from above and below. There is also a pair of blocks which slide forward and back between the blade guides. These are the blade gibs and their job is to prevent the blade from moving backwards under pressure from the work being fed into it. They have to be adjustable because the blade gets a little narrower every time it's sharpened. As everyone who's operated a bell skiver understands, the position of the blade edge, relative to the feed wheel, is essential. Everything has to be very flat and smooth. And this is what I saw when I removed the top guide:

Yep, that's rust. On precision ground surfaces. So, choking on the emulsifying oil I sprayed all over the machine and myself I set about with rags and a flat-head screwdriver scraping off what I could. (For reference we're looking down onto the top of the machine from the front. That big knurled wheel is the thickness adjuster. The knife runs in the groove just visible above the adjuster, and the gibs are the two narrow steel blocks immediately above the groove.

Big improvement and probably as good as I'm going to get it without removing more mechanism than I wanted to, or getting in there with a dremel. This photo is taken backwards form the previous and was after I'd removed the gibs for polishing. The knife groove is a little more visible here, as indeed is the back edge of the knife, far too far forward for actual use.

[Matt S]

A little more of the endless endlessness, you lucky people.

With the blade in its proper place and the gibs moving smoothly it's time to adjust the tracking. This is a minute adjustment of the angle of the idler wheel, which changes the angle of the knife. Just like a bandsaw or belt sander. The idea is that the back of the knife bears evenly on both gibs, judged by comparing how warm each feels after running for a while. The previous owner of mine apparently had the knife running at an angle for long enough to wear a deeper groove in the right gib than the left so it can never run true. I didn't feel confident grinding the wear surfaces level with enough accuracy and couldn't find any for sale online. So I shimmed the right-hand gib. There's only one type of shim-stock I had handy, and it comes wrapped around beer.

Much better.

[bermudahwin]

5 hours ago, Matt S said:

There's only one type of shim-stock I had handy, and it comes wrapped around beer

No non-alcoholic versions around, I presume? From your PM yesterday I had presumed a leaning to H&S

Doing well on an interesting project there, Matt.

 

[RockyAussie]

5 hours ago, Matt S said:

A little more of the endless endlessness, you lucky people.

With the blade in its proper place and the gibs moving smoothly it's time to adjust the tracking. This is a minute adjustment of the angle of the idler wheel, which changes the angle of the knife. Just like a bandsaw or belt sander. The idea is that the back of the knife bears evenly on both gibs, judged by comparing how warm each feels after running for a while. The previous owner of mine apparently had the knife running at an angle for long enough to wear a deeper groove in the right gib than the left so it can never run true. I didn't feel confident grinding the wear surfaces level with enough accuracy and couldn't find any for sale online. So I shimmed the right-hand gib. There's only one type of shim-stock I had handy, and it comes wrapped around beer.

Much better.

Hey @Matt S, Congrats on obtaining a splitter. Just a thought on those wear blocks (gibs) check the depth of the groove wear in them as they can help generate excessive heat if they come over more than 1/2 mm or so. The excess wear on the right is normal as the way the blade spins it is the first to cop the pressure. I normally grind them down until there is only a minor wear line from the blade left and check from there. The steel is super hard like tungsten or something on both the Elbiko  and the Comoga I have, but interestingly the Comoga also came with a few extra wear block that I think are teflon or some extra hard nylon at any rate. They do wear faster but don't seem to generate the heat as much. If the heat is too much it transmits through the blade and you will find that they put cracks all around and through the blade until of course they snap through. The German blades are better and last way better. Feel the back of the blade occasionally and sand of any excessive burring. On the adjuster for adjusting the blade forward there is a spring that pushes a steel tab into the toothed wheel you turn by hand. It is not in your pictures but I assume you have it and the tab piece. Make sure that spring is fairly strong as some times when the leather goes through it can knock the adjuster back and of course the blade goes back with it. Better to check now and not have to pull it all off and have to go through the joy of having to carefully adjust the top plate down again. Amazing how a great hunk of steel can bend around like butter. Last thing ....check that the blowers air intake is clear and that there is plenty of air flow blowing down the chute right across. Just hold a leather strap in the chute and see if it shakes around and wants to go through. Some times the chute can get clogged up and it is super annoying when you find that the leather your trying to feed through is obstructed by a build up of waste in the chute. This is one reason I like my old Albeko better as it's waste comes out to the front and straight into a bin to the side. Have fun and again congratulations on a fine pick up.

 

 

 

[jimi]

Great stuff Matt, Its looking good...

[Matt S]

4 hours ago, RockyAussie said:

Hey @Matt S, Congrats on obtaining a splitter. Just a thought on those wear blocks (gibs) check the depth of the groove wear in them as they can help generate excessive heat if they come over more than 1/2 mm or so. The excess wear on the right is normal as the way the blade spins it is the first to cop the pressure. I normally grind them down until there is only a minor wear line from the blade left and check from there. The steel is super hard like tungsten or something on both the Elbiko  and the Comoga I have, but interestingly the Comoga also came with a few extra wear block that I think are teflon or some extra hard nylon at any rate. They do wear faster but don't seem to generate the heat as much. If the heat is too much it transmits through the blade and you will find that they put cracks all around and through the blade until of course they snap through. The German blades are better and last way better. Feel the back of the blade occasionally and sand of any excessive burring. On the adjuster for adjusting the blade forward there is a spring that pushes a steel tab into the toothed wheel you turn by hand. It is not in your pictures but I assume you have it and the tab piece. Make sure that spring is fairly strong as some times when the leather goes through it can knock the adjuster back and of course the blade goes back with it. Better to check now and not have to pull it all off and have to go through the joy of having to carefully adjust the top plate down again. Amazing how a great hunk of steel can bend around like butter. Last thing ....check that the blowers air intake is clear and that there is plenty of air flow blowing down the chute right across. Just hold a leather strap in the chute and see if it shakes around and wants to go through. Some times the chute can get clogged up and it is super annoying when you find that the leather your trying to feed through is obstructed by a build up of waste in the chute. This is one reason I like my old Albeko better as it's waste comes out to the front and straight into a bin to the side. Have fun and again congratulations on a fine pick up.

Thanks mate. My calipers wouldn't fit in the tiny groove but measuring with my mk1 thumbnail I reckon it's less than 1/2mm deep. Do you have some special arrangement for grinding them? The blade is pretty clean apart from a few minor rust spots.

Yep the adjuster spring is present and pretty firm. What should I look for when snugging down the top plate?

Blower's working okay but I've got it disconnected right now as it was running a little warmer than I thought right and I don't need it for the adjustments I'm making right now.

3 hours ago, jimi said:

Great stuff Matt, Its looking good...

Thanks Jimi, it's really coming together now. Despite a few maintenance issues it's not in bad nick for its age!

5 hours ago, hwinbermuda said:

No non-alcoholic versions around, I presume?

Tea bag boxes ya mean Harry? Not so good for shimming steel-on-steel.  (Actually I've shimmed steel-on-wood bearing surfaces with card before. Soak the card in linseed oil before snugging down and it polymerises to a hard, firm surface that can be peeled off with no damage if you need to. Works great on Lee Enfields where the wood has shrunk a little.)

[Matt S]

Quick question for anyone who's operated a splitter like this before: could you please describe the action of the grinder timer? Mine has never worked, it's beyond economical repair and I've decided just to replace it. The manual says to set it for 10-15 minutes depending on how tough is the work. But what it doesn't say is what the operation of the timer actually is. Is it, for instance, an interval timer where it switches on for 1 minute, off for 10 minutes then on again ad infinitum, or an on-delay timer where it's manually switched on but switches itself off after 10 minutes.