I bought a band-knife splitter

[bermudahwin]

48 minutes ago, Matt S said:

Tea bag boxes 

I thought the ubiquitous Red and White soda cans,

[Danne]

I really like to follow your work on this splitter, and I'm looking forward to updates. Do you have an exploded view/parts list of the gibs and "guides" It would be nice with individual adjustment for the gibs. I'm thinking something like this (If i understand the construction correctly.) This way you could regrind your "guides" individually if needed.

 

Edited March 7, 2019 by Danne

[RockyAussie]

9 hours ago, Matt S said:

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.

Mine are inoperative as well and I would not want them operating anyway. A lot of factors come in to how often a blade will need to be sharpened and generally 30 seconds to a minute is fine. Some leathers, even soft leathers will blunt a blade in no time and some you can go for a half hour or more. Generally the split will start to look choppy and sawn and therefore it needs to be sharpened. Except for foam I never have the blades sharpening while splitting and that is rare as well. A new blade can take a half hour to sharpen. Make sure to clean the felt guides well when changing the blade and on the odd occasion as well. I tend to scrape them with a knife and sometimes rough sand them if they need it.The blade should be fine sandpapered to get rid of the rust and sometimes I give the blade a light sand on the run but THAT IS SUPER DANGEROUS and absolute full undivided attention is a must. I should be saying DONT do it. Make sure the blade only barely wants to go backward toward the wear blocks (gibs) and do plenty of quick stop starts after to check that it does. TOO much will create overheating of the blade and wear blocks. New full size grindstones will make sharpening a matter of seconds instead of minutes unless your rubber belt that runs the grindstones is overstretched and worn out. Another reason why auto is no good. With regards to the top plate tightening it would be best to check with the manual. My Comoga has 11 screw downs with 11 screws to set the stop points. Main thing is when the blade is in position when you do the front ones up and they put any pressure on the blade when you are hand turning it you back it off just barely and reset the stopper. A piece of paper should be too thick to go between the blade and the upper or lower plates at the front. I try and get all bolts to touch and then back off until I can turn the blade just freely. If it can deflect up or down overly then so can your thicknesses. Getting the blade to show even amounts either side when sharpening is a must and helps to keep the blade in the middle of the gap and therefore the consistency of the split thickness.

8 hours ago, Danne said:

I really like to follow your work on this splitter, and I'm looking forward to updates. Do you have an exploded view/parts list of the gibs and "guides" It would be nice with individual adjustment for the gibs. I'm thinking something like this (If i understand the construction correctly.) This way you could regrind your "guides" individually if needed.

 

@Danne The idea looks good and your drawing skills are excellent but I have to say the person doing the adjustments would have to know these machines very well. Is it desirable that both blocks should be the same measurement and if not what should it be??? When you cut a piece of leather by hand is it easier to have a broad flat blade and cut in one hit or a angled blade that slices through? How important is it to run the job exactly in the centre? Many job pieces are not square so that changes the pressure points as does the spring pressures left as against right on the feed roller. The variables in that area are a more difficult thing to get adjusted to be suitable and improvements in that area are more important in an engineering sense to me. So far if a piece comes through thick one side and thin the other you either may need to adjust one side tighter or looser or sometimes just move the job further to one side. I do think your idea has merit but perhaps only in the manufacturing stage as elongating the slots would take a fair bit of expense for the little bit gained.

[Danne]

38 minutes ago, RockyAussie said:

@Danne The idea looks good and your drawing skills are excellent but I have to say the person doing the adjustments would have to know these machines very well. Is it desirable that both blocks should be the same measurement and if not what should it be??? When you cut a piece of leather by hand is it easier to have a broad flat blade and cut in one hit or a angled blade that slices through? How important is it to run the job exactly in the centre? Many job pieces are not square so that changes the pressure points as does the spring pressures left as against right on the feed roller. The variables in that area are a more difficult thing to get adjusted to be suitable and improvements in that area are more important in an engineering sense to me. So far if a piece comes through thick one side and thin the other you either may need to adjust one side tighter or looser or sometimes just move the job further to one side. I do think your idea has merit but perhaps only in the manufacturing stage as elongating the slots would take a fair bit of expense for the little bit gained.

4

My experience with splitting machines is "I have seen a machine one time"  But I have worked a lot with old machines with high tolerances, and also worked as a CNC-programmer. And I hope to find an old Fortuna splitting machine. Preferably something broken that needs repair.  (I don't need one, since this is my hobby, and I'm looking for a bell knife skiving machine too, which is a lot less complicated and would work as a splitter for my smaller projects (Wallets, watch straps)

So the time it would take me to repair it and "figure out" the machine doesn't matter. When I read your answer to Matt, it's clear you have good knowledge of these machines. Your machine work because you understand HOW it works. 

Of course what you say make sense. why should he have someone to manufacture those "adjustment parts" for him? A better solution would be to ask a shop to regrind his wear guides together with a surface grinder when needed?

If you have a user manual and/or parts list/exploded view of any band knife splitting machine it would be very interesting to look through them if you want to share.

 

Btw, thanks for sharing your knowledge here, I find it very interesting.

 

 

[Matt S]

On 3/7/2019 at 2:54 PM, Danne said:

I really like to follow your work on this splitter, and I'm looking forward to updates. Do you have an exploded view/parts list of the gibs and "guides" It would be nice with individual adjustment for the gibs. I'm thinking something like this (If i understand the construction correctly.) This way you could regrind your "guides" individually if needed.

Tack, Danne I'm glad you're enjoying it. I'm sorry it's such a strung-out saga but I'm spending the odd hour on this machine whenever I can around my other commitments. Right now I don't have the time or resources to properly rebuild this machine (and I don't think it really needs it) so regrinding the the gibs is something I'm avoiding if at all possible and for now.

On 3/7/2019 at 11:55 PM, RockyAussie said:

Mine are inoperative as well and I would not want them operating anyway. A lot of factors come in to how often a blade will need to be sharpened and generally 30 seconds to a minute is fine. Some leathers, even soft leathers will blunt a blade in no time and some you can go for a half hour or more. Generally the split will start to look choppy and sawn and therefore it needs to be sharpened. Except for foam I never have the blades sharpening while splitting and that is rare as well. A new blade can take a half hour to sharpen. Make sure to clean the felt guides well when changing the blade and on the odd occasion as well. I tend to scrape them with a knife and sometimes rough sand them if they need it.The blade should be fine sandpapered to get rid of the rust and sometimes I give the blade a light sand on the run but THAT IS SUPER DANGEROUS and absolute full undivided attention is a must. I should be saying DONT do it. Make sure the blade only barely wants to go backward toward the wear blocks (gibs) and do plenty of quick stop starts after to check that it does. TOO much will create overheating of the blade and wear blocks. New full size grindstones will make sharpening a matter of seconds instead of minutes unless your rubber belt that runs the grindstones is overstretched and worn out. Another reason why auto is no good. With regards to the top plate tightening it would be best to check with the manual. My Comoga has 11 screw downs with 11 screws to set the stop points. Main thing is when the blade is in position when you do the front ones up and they put any pressure on the blade when you are hand turning it you back it off just barely and reset the stopper. A piece of paper should be too thick to go between the blade and the upper or lower plates at the front. I try and get all bolts to touch and then back off until I can turn the blade just freely. If it can deflect up or down overly then so can your thicknesses. Getting the blade to show even amounts either side when sharpening is a must and helps to keep the blade in the middle of the gap and therefore the consistency of the split thickness.

Thanks fella. The top blade on mine is only held in place with two countersunk hex-socket screws. I tightened them according to the manual, which was pleasantly simple. No torque ratings, no fannying about, just tighten but not too much that the plate stops rocking on its springs. Then tighten the locking eccentrics so the guide stops rocking and then tighten their locking screws. Those are the sorts of instructions even I can follow. I checked and I can't get a piece of copy paper between the knife and either guide but can turn the knife over by hand. Excellent engineering.

I've solved the mysteries of the auto sharpening feature. In case someone comes across this thread in the future is also trying to fathom it out, the timer appears to be an interval timer that sends out a ~0.5sec 220v pulse between each interval. I.e. if you set it at 10 minutes it'll close the contacts for half a second, then off for 10 minutes, close the contacts for 0.5sec again, ad infinitum. A simple thing to replicate using off-the-shelf parts if you're so inclined.

The timer does not output to a clutch or an electronic control for the grinding motor as I suspected but to a solenoid directly behind the knife advance wheel. For each pulse it receives it advances the knife one notch. I presume that this brings the knife edge heavily into contact with the emery wheels and the edge is ground back by the same amount. I've hooked it up to a temporary toggle switch inside the electrical panel but I doubt I'll get into the habit of using it for all the reasons Rocky said.

On 3/8/2019 at 1:04 AM, Danne said:

My experience with splitting machines is "I have seen a machine one time"  But I have worked a lot with old machines with high tolerances, and also worked as a CNC-programmer. And I hope to find an old Fortuna splitting machine. Preferably something broken that needs repair.  (I don't need one, since this is my hobby, and I'm looking for a bell knife skiving machine too, which is a lot less complicated and would work as a splitter for my smaller projects (Wallets, watch straps)

So the time it would take me to repair it and "figure out" the machine doesn't matter. When I read your answer to Matt, it's clear you have good knowledge of these machines. Your machine work because you understand HOW it works. 

If you have a user manual and/or parts list/exploded view of any band knife splitting machine it would be very interesting to look through them if you want to share.

This was about the limit of my knowledge of band-knife machines too until I bought this one, though I don't have nearly your engineering skill. I was fortunate enough to be in the right place at the right time and had to jump on the chance, though I spent the money I had budgeted for some cutting dies I sorely needed (and still need). Apart from the labour (which was mostly days off and evenings) I've spent about 5-6% the cost of a new machine on this one.

Bell-knife skivers are real handy machines. You can do some small splitting with one (and I do... or did...) but I've never got it setup so I'm happy with the finish if I have to do multiple passes. The largest roller-foot I have is 40mm and it has sharp edges so if the leather's any wider than that I end up with tram lines. The error is probably between the seat and the machine in my case, but that's my experience.

I've got a few PDF manuals I can send along if you're curious but I don't think there's many/any exploded diagrams. Mostly line drawings of sub-assemblies if their function is not immediately clear.

[Danne]

12 hours ago, Matt S said:

Tack, Danne I'm glad you're enjoying it. I'm sorry it's such a strung-out saga but I'm spending the odd hour on this machine whenever I can around my other commitments. Right now I don't have the time or resources to properly rebuild this machine (and I don't think it really needs it) so regrinding the the gibs is something I'm avoiding if at all possible and for now.

Thanks fella. The top blade on mine is only held in place with two countersunk hex-socket screws. I tightened them according to the manual, which was pleasantly simple. No torque ratings, no fannying about, just tighten but not too much that the plate stops rocking on its springs. Then tighten the locking eccentrics so the guide stops rocking and then tighten their locking screws. Those are the sorts of instructions even I can follow. I checked and I can't get a piece of copy paper between the knife and either guide but can turn the knife over by hand. Excellent engineering.

I've solved the mysteries of the auto sharpening feature. In case someone comes across this thread in the future is also trying to fathom it out, the timer appears to be an interval timer that sends out a ~0.5sec 220v pulse between each interval. I.e. if you set it at 10 minutes it'll close the contacts for half a second, then off for 10 minutes, close the contacts for 0.5sec again, ad infinitum. A simple thing to replicate using off-the-shelf parts if you're so inclined.

The timer does not output to a clutch or an electronic control for the grinding motor as I suspected but to a solenoid directly behind the knife advance wheel. For each pulse it receives it advances the knife one notch. I presume that this brings the knife edge heavily into contact with the emery wheels and the edge is ground back by the same amount. I've hooked it up to a temporary toggle switch inside the electrical panel but I doubt I'll get into the habit of using it for all the reasons Rocky said.

This was about the limit of my knowledge of band-knife machines too until I bought this one, though I don't have nearly your engineering skill. I was fortunate enough to be in the right place at the right time and had to jump on the chance, though I spent the money I had budgeted for some cutting dies I sorely needed (and still need). Apart from the labour (which was mostly days off and evenings) I've spent about 5-6% the cost of a new machine on this one.

Bell-knife skivers are real handy machines. You can do some small splitting with one (and I do... or did...) but I've never got it setup so I'm happy with the finish if I have to do multiple passes. The largest roller-foot I have is 40mm and it has sharp edges so if the leather's any wider than that I end up with tram lines. The error is probably between the seat and the machine in my case, but that's my experience.

I've got a few PDF manuals I can send along if you're curious but I don't think there's many/any exploded diagrams. Mostly line drawings of sub-assemblies if their function is not immediately clear.

8

"I've spent about 5-6% the cost of a new machine on this one." Wow, sounds like you made a really good deal. 

Regarding splitting with a skiving machine. As I said I have no experience there either. But I have seen people split leather with good results. (Softer leather like chevre sully or alligator and such.) I have seen different types of presser feet, some have slightly rounded edges. 

I would really appreciate the pdf-manuals you have. I really hope you get this machine into full working condition.

 

[Matt S]

5 hours ago, Danne said:

"I've spent about 5-6% the cost of a new machine on this one." Wow, sounds like you made a really good deal. 

Regarding splitting with a skiving machine. As I said I have no experience there either. But I have seen people split leather with good results. (Softer leather like chevre sully or alligator and such.) I have seen different types of presser feet, some have slightly rounded edges. 

I would really appreciate the pdf-manuals you have. I really hope you get this machine into full working condition.

Like I say I couldn't turn the opportunity down. It's not been a free ride -- I've probably put nearly 100 hours' work in over the past few months so if I were turning down paid work the price comes near to what dealers charge for a refurbished machine like this. However I've learned a lot about how this machine works and I've enjoyed myself hugely. The latest Camoga machines are half the weight and I suspect much quieter and more user friendly. They are, however, eye-wateringly expensive.

Splitting with a skiver is certainly possible. Mine doesn't take new-style feet without more adjustment than I'd like and I want to keep the sharp corners on my roller foot because it gives excellent step skives.

Re. the manuals I'll send you a PM.

[Danne]

21 minutes ago, Matt S said:

 Like I say I couldn't turn the opportunity down. It's not been a free ride -- I've probably put nearly 100 hours' work in over the past few months so if I were turning down paid work the price comes near to what dealers charge for a refurbished machine like this. However I've learned a lot about how this machine works and I've enjoyed myself hugely. The latest Camoga machines are half the weight and I suspect much quieter and more user friendly. They are, however, eye-wateringly expensive.

Splitting with a skiver is certainly possible. Mine doesn't take new-style feet without more adjustment than I'd like and I want to keep the sharp corners on my roller foot because it gives excellent step skives.

Re. the manuals I'll send you a PM.

If you bought a refurbished machine, it would be nice at first, but soon you would probably discover you need to learn how everything works, all those small important adjustments you need to do.

A new Camoga like the Camoga Compact have automatic knife trend setting. Easy to replace knife, and switch between roll/bar. But I’m sure the build quality is not like the old machines. 

[Matt S]

On 3/10/2019 at 9:23 PM, Danne said:

If you bought a refurbished machine, it would be nice at first, but soon you would probably discover you need to learn how everything works, all those small important adjustments you need to do.

A new Camoga like the Camoga Compact have automatic knife trend setting. Easy to replace knife, and switch between roll/bar. But I’m sure the build quality is not like the old machines. 

A new one would be better for sure, probably in every regard except for price. When I priced the Camoga Compact late last year it was in the region of a new hatchback. Dealer refurbished similar machines to mine are in the region of a 10-year-old hatchback. Mine cost less than a month's minimum wage. I can tolerate a lot of manual tracking/trend adjustment for that price difference!  And even mine is pretty simple to switch between bar and roll -- two screws and no adjustments necessary.

It's probably no surprise but I couldn't wait to try a split and yes I've put a few offcuts through for testing. Mostly it has highlighted specific areas where I need to adjust or clean the machine. Long, boring story short I've been knocking them down in turn. Not many photos as there's not a great deal of point in a string of "here's some oily rust and here it is gone" photos. Knife was pretty sharp but a few grinds (once the emery wheels were adjusted) increased the smoothness of the cut.

The biggest issues were around the depth of split. In just a couple inches of distance the knife was plunging up and down. Variance of maybe +- 0.5mm which is well above the acceptable range. After getting the knife exactly at the zero-setting (its optimal distance from the feed roll) things improved a little. Figuring that the feed roll assembly isn't moving up and down as smoothly as if it were perfectly clean I increased the presser tension and my splits started being longitudinally consistent. Presser tension is a little higher than I would expect from the manual but still within the bounds of normality.

Now I moved to calibrating the thickness scale. As with many such things I know that I can't just rely on what's on the dial -- I will always have to check the split piece with the gauge for accuracy. However having the scales as close as possible to the expected output would be pretty handy -- it'll let me get to it with far fewer trials.

There's a coarse readout on the RHS of the machine in whole millimeters. The scale can be slipped so that was easily adjusted but the fine thickness readout (in tenths of millimeter) is on the thickness adjuster itself. I had to strip the presser assembly fairly extensively in order to fix an issue with the drive and I presume that I got them slightly out of goose when I did that, though I don't know if they were accurate when I bought the machine. The manual did not describe how it's supposed to be done so I split a piece of leather, measured its thickness, then fettled the readouts until they tallied.

Not quite knowing what I was doing I made an educated stab in the twilight and loosened these two nuts either side of the adjuster. This took a bit of pen oil and elbow grease.

 

This allowed the adjuster to be rotated in reference to the two axles on which it runs, so it reads the same as what the leather has just split to. (This was a three-handed job.) Then tighten up the nuts. (This was a 5-handed job.) Notice that there are two fine readouts -- once for when the presser bar is fitted (to the left of the wheel) and one for when the presser roll is fitted (to the right of the wheel). I have mine fitted with the feed roll.

 

Then set for a specific thickness (say 2.0mm) and test.

That'll do I reckon.

[chrisash]

Tut Tut , That "that will do attitude" matt, your old headmaster would shake his head