Getting a bell knife skiver to work.

[keithski122]

Hi. My name is Keith and I need your help please.

I've recently bought a preowned global skiver(fortuna copy) as where I work we had a very old fortuna that I did not own and could never get to work correctly.As I didn't want to pay for parts on something that wasn't mine I bout the global machine.It works better than the fortuna but I cannot get it to give a consistant cut.Leather used is upholstery type(1.1mm), stone type wheel, 50mm foot and servo motor.I'm trying to get the edge skived for about 10mm.

I think I've read every internet post and seen every video posted but cannot work it right.The wheel grabs the leather and doesn't feed smoothly, would a different material feed wheel help?

Is it easier to set for a wedged skive or a flat skive?

Some videos I've seen they skive it, its not thin enough so turn the knob, reskive until thin enough.I do this and it takes nothing off, turn knob, nothing off, turn knob .......cut through leather.How much should I  need to turn knob each time, 1/8 turn , 1/4, 1/2 ?

Would a smaller foot help?

I've sharpened blade by holding a sharpie on the blade to colour edge, then ground until edge nice and shiney, then used the hand stone to deburr.

Which postition is it best to have the drive belts on?

Which position for the feed tension spring

Pics show the machine I bought and what I would like to achieve.

Many thanks for any help.

 

[keithski122]

Heres a couple of pics I took a few months ago of the results I'm getting.

[Matt S]

Hi Keith. You're certainly not the first to have an issue with a bell-knife skiver -- they're notoriously finicky machines. For any particular job there's usually quite a narrow window between all the various variables and it takes a bit of playing to get an instinctive feel for where it is. However, once you have it dialled in right it should be able to do that job very easily. Bear in mind that most of my experience with such machines is working on heavily waxed chrome-tanned cow leather around 2mm thick. However I have skived a fair bit of upholstery leather also, and played around with 3+mm bridle.

I have my belts setup so the knife turns as fast as possible in relation to the feed wheel. This gives it a cleaner cut and minimises ripples, at least with the leathers I use.

I don't know if a smaller foot would help but find, especially with "grabbier" leather", that a roller foot helps things work much easier than a "fixed" one.

My feed wheel spring is usually set on... 2 of 5? About middle of the range. The old boy I bought mine off said that that works for most leathers and so far he's been right.

Have you tried adjusting the feed wheel height, angle and spring pressure? Knife position? 

There's many different types of feed wheel available but I think the one you have will work well with that leather. Another tip the old boy taught me was to not rely on the feed wheel alone -- especially with more delicate and/or softer leathers that it should just provide a little forward inclination to the leather, and that the operator should provide the majority of the impetus. This reduces its tendency to bunch up, which can cause the knife to cut through the leather.

[keithski122]

Thanks for the reply.I don't have much chance to play with it as its at work and we're so stacked with work I don't have much spare time, shame as it will be a great asset when i have got it dialed in. I have had it with the belt both to the far right pulleys and to the far left (I think its at the left at the moment which I think is slow blade fast feed), I don't suppose you could have a look and tell me which yours is on. I have thought of buying an extra motor and driving feed and blade off separate motors.

I have followed a few videos in setting up but not to any success, probably down to me not the videos.At the moment I have the blade about 0.5mm away from the foot.

Do you know what controls the finished thickness ? Is it foot to feed distance, foot to blade distance(left to right), foot to blade distance (up/down), blade to feed distance or just a mix of all?

[jimi]

Here is a link for another thread on skivers which has a manual for download in PDF

I think your blade for normal leather is 0.3-0.4 from the foot, thick leather 0.5 and thin like goat 0.2. I have mine set at about 0.2-0.3 for 1-1.4 mm thick Horse leather and works fine. If you have a roller foot on then settings will change, according to the manual, depending on the roller used and also the thickness of the leather.I have the distance between the stone feed and the knife at 0.1 mm,The blade has to be very sharp. Also if you are bevel skiving then the traction spring (which is on the front facing you) should be less than the traction spring for lifting and lowering (to the back left hand side) allowing the feed wheel to tilt, if you are parallel skiving then the other should be tighter allowing it to lift parallel to the knife. If it is any help i have a servo fitted at the moment on the skiver and it runs at number 10 which is i think is about 1100-1200 Rpm. this is spinning all the time and the feed wheel is actuated by a clutch. It looks to me like possibly your knife is not sharp, also because you said you turn the knob and no cut? You might need to clean the feed stone if it is clogged up with dirt.I use a soft wire brush.The thickness of the cut is done by adjusting your foot in height, the angle of the cut by tilting the foot and the width by moving the guide forwards or backwards. If you are looking to do the same as in the picture then for the edge you can use a normal foot and adjust the skiving width if the foot is wider but for those skives on the inside of the holes in the middle of the cover you will need a foot with the portion that skives on the tip of the foot only. hope this helps.

Edited March 23, 2019 by jimi

[Matt S]

Here's a very good set of instructional videos on the bell-knife skiver: 

 

As usual these videos by Checaflo are full of common sense solutions to things that I would overthink. I love, for instance, his use of pieces of different papers as feeler gauges -- they cost nothing, you'll always have some lying around and they don't take any time to make. They're also really effective -- it's how I now get a "starting" set of adjustments, and tweak from there after trying it out on scraps.

17 hours ago, keithski122 said:

Thanks for the reply.I don't have much chance to play with it as its at work and we're so stacked with work I don't have much spare time, shame as it will be a great asset when i have got it dialed in. I have had it with the belt both to the far right pulleys and to the far left (I think its at the left at the moment which I think is slow blade fast feed), I don't suppose you could have a look and tell me which yours is on. I have thought of buying an extra motor and driving feed and blade off separate motors.

I have followed a few videos in setting up but not to any success, probably down to me not the videos.At the moment I have the blade about 0.5mm away from the foot.

Do you know what controls the finished thickness ? Is it foot to feed distance, foot to blade distance(left to right), foot to blade distance (up/down), blade to feed distance or just a mix of all?

My belt is on the far left, which is slightly less than a 1:1 ratio -- slow feed fast knife. The ratios inside your machine may be different. Running off a 1450RPM clutch motor FWIW, though the motor pulley is maybe twice the diameter of the skiver's pulley. I tend to run it with the pedal to the metal  so the knife is probably doing about 3000 RPM. Yes you can buy a second motor and have the feed and knife totally independent. It's something I intend to do with mine one day.

As said by Jimi above, finished thickness is primarily affected by the height of the presser foot. I suggest you try to get your knife closer to the foot. I like to bring the knife in until it touches the foot and back it off just enough to remove contact (all being turned by hand -- motor off). This is the position where a fresh clean piece of cheap copy paper just slides between the foot and the knife.

[keithski122]

Thanks for the advice. I've decided to get an engineer in to set it up and show me how to work it.Only so much time I can spend fiddling with it and getting nowhere, otherwise its just an expensive space filler.