Skiving Machine Ripping Leather, please help !

[SonderingSusan]

Hey Everyone,

 

If anyone has any advice at all / any suggestions i would be so so grateful. My skiving machine has started ripping my leather and i don't know why/ or what to do. I can't find a skiving machine technician anywhere in the country and don't know from what other profession someone could possibly help/ have the required skills to look a the blade. 

Here are some pictures of what is happening. All/ any help is greatly appreciated ! Thanks!

[SonderingSusan]

 

Above is a link to a picture of the rip in the leather.

[SonderingSusan]

[Ferg]

You aren't going to like the "fix" I am going to suggest. lol

Power skivers that are considered "consumer grade", most of them, do not do well with Chrome tanned leather especially if it is of soft composition. I gave up wasting chrome tanned leather with mine some time ago. I have a small round knife I do all of my skiving with, except veg tanned.

Some heavier weight Chrome tanned will work fair, it just wasn't worth the time and money wasted.

The actual Fortuna skivers may handle this better, I am not spending that much money for a skiver to find out.

Ferg

[SonderingSusan]

Thanks Ferg!

 

I really appreciate your input, so what your saying is that I'm not really doing anything wrong? its just the model of skiver i have coupled with the chrome leather? 

Okay ! Well thanks for the info , much appreciated !

[Sonydaze]

I'm presuming that you have a drum skiver.  The cutting edge of the drum needs to be advanced to very close to the presser foot and then sharpened.  If you have not advanced/sharpened the cutting drum frequently, you likely have to do a long grind to get the bevel on the drum back to how it should be.  Properly adjusted and very sharp, we can skive the edges of upholstery leather.  It doesn't work perfectly all the time, but we get the job done.

[Ferg]

Get yourself a piece of at least 1/4" thick glass. Mine is round and probably 18" in diameter. Edge needs to be ground so you don't get cut on the edges. Lay the leather piece you wish to skive upside down on the glass, holding it with left/right hand. Watch the blade, they need to be very sharp and they will cut a finger in the blink of an eye.

If you have a round knife or skiving blade, allow the edge of the knife to ride on the surface of the glass. Other edge of blade should be held so it cuts an angled skive on the leather.

It takes a little practice but you can get very good at it. I can skive by hand faster than I can with the powered skiver and I don't need to throw anything away.

In the photo I have the leather on my piece of glass, the right edge of the knife is resting on the glass.

[electrathon]

I agree with Sonydaze. your blade is likely dull and possibly out of adjustment.  Once sharp you can make perfect skives in seconds.  The reason for the ragged edge is the knife is not cutting clean.  Take a sharpie and paint the cutting area on the bell knife.  Touch the stone to it and grind gently till the sharpie mark is cleaned off.  You may need to roll the burr off the inside of the bell with a round dowel too.  My skiver chewed leather when I got it, learned how to sharpen it and it works well now.

[Sonydaze]

If this fixes it, don't feel bad, I think almost everyone with a drum skiver has learned this the hard way. I have yet to see a machine with a good instruction manual.

[BillyBuck]

Why are you skiving on that side of the leather? From what I see in your pictures you should be skiving on the other side of the leather.

[RockyAussie]

Nice pics of what the culprit has done but none of the culprit? Please see below one of my skivers that is now in need of a sharpen. Take no notice of the brass roller that is just something I made up to make soft and glazed crocodile easier to skive. Its just a bit of brass i shaped down to match the grind stone feed wheel in shape and a concrete nail smoothed out and put through.Helps to stop friction. Please send some close up pics of your machine to analyze.Do you have the dressing stick for inside bell and do you know how to use it?

[Art]

The Chinese skivers are not too bad.  The German ones are a little better put together, and if I was running one all day every day, it would be German.  I have a Chinese top and bottom feed skiver.  This machine is really great on veg tan.  The bottom feed models are great on chrome tan and soft veg.  The bottom feeds have presser feet and three are supplied, and it isn't terribly hard to make special ones.  The top and bottom feed models use a roller presser foot and custom ones are rather technical (hence pricey), but with the skiving we do the one provided works great.  Son does garment and cosPlay work on it and he has no trouble doing chrome tan.  If I were to modify the one I have, I would put a second motor on, or a clutch setup to continuously run the bell knife and intermittently run the feed.  The two motor system would allow for variable speed on the feed although, we run the feed full bore all the time.  

It is necessary to have a sharp and well adjusted blade for optimal operation.  It takes a good long time to grind the knife. It can take 5 minutes to sharpen a dull knife; I use the sharpie method, take a good bite with the wheel and just let it run until it stops making any grinding noise, then shut it off and see that all the sharpie mark is gone.  Put the sharpie around the whole knife edge and remove all of it.  Don't get sloppy and put sharpie in a huge wide strip, just the edge.  If your first sharpening doesn't remove all of the sharpie, repeat until it does.  After the sharpening, use a hone you can get from Osborne or Wolff Industries, red is fine, white is extra fine.  You could sharpen a 1953 Packard bumper with the stick they provide with the machine. All you want to do to the back of the edge is to remove any burr, you are not sharpening anything.  If you can't get the hone into the knife or it causes some trepidation, tie the hone to a stick (the hone I referenced is 4 inches long).  The hones are inexpensive, around $6 or so.

Lastly, move the bell knife in so the edge is right next to the feed wheel.  The front portion of the feed wheel will be under the edge of the bell knife, but not touching.  Adjust the feed wheel until it skives the way you want.  I think there is a setup video by Campbell-Randall or Shoe School on youtube.  After it skives the way you want, leave it alone, or make minute adjustments as required.

Art

[SonderingSusan]

On July 14, 2016 at 7:11 PM, Sonydaze said:

I'm presuming that you have a drum skiver.  The cutting edge of the drum needs to be advanced to very close to the presser foot and then sharpened.  If you have not advanced/sharpened the cutting drum frequently, you likely have to do a long grind to get the bevel on the drum back to how it should be.  Properly adjusted and very sharp, we can skive the edges of upholstery leather.  It doesn't work perfectly all the time, but we get the job done.

Thanks  @Sonydaze for the advice is very helpful!  Yes it has been so hard to get to grips with the skiving machine and learn what adjustments do and they affect the outcome . So thanks for the advice about the position of the cutting edge ! And all the other advice / encouragement ! I think my problem was that i wasn't sharpening the bell knife at the right place. I reached in and moved the grinding stone on with my hand and it seemed to make better contact with the bell knife and give a better sharpen. It seems the only way i can move the grinding stone is manually , is this correct procedure?

Thanks again,

S

[SonderingSusan]

On July 15, 2016 at 8:30 PM, Art said:

The Chinese skivers are not too bad.  The German ones are a little better put together, and if I was running one all day every day, it would be German.  I have a Chinese top and bottom feed skiver.  This machine is really great on veg tan.  The bottom feed models are great on chrome tan and soft veg.  The bottom feeds have presser feet and three are supplied, and it isn't terribly hard to make special ones.  The top and bottom feed models use a roller presser foot and custom ones are rather technical (hence pricey), but with the skiving we do the one provided works great.  Son does garment and cosPlay work on it and he has no trouble doing chrome tan.  If I were to modify the one I have, I would put a second motor on, or a clutch setup to continuously run the bell knife and intermittently run the feed.  The two motor system would allow for variable speed on the feed although, we run the feed full bore all the time.  

It is necessary to have a sharp and well adjusted blade for optimal operation.  It takes a good long time to grind the knife. It can take 5 minutes to sharpen a dull knife; I use the sharpie method, take a good bite with the wheel and just let it run until it stops making any grinding noise, then shut it off and see that all the sharpie mark is gone.  Put the sharpie around the whole knife edge and remove all of it.  Don't get sloppy and put sharpie in a huge wide strip, just the edge.  If your first sharpening doesn't remove all of the sharpie, repeat until it does.  After the sharpening, use a hone you can get from Osborne or Wolff Industries, red is fine, white is extra fine.  You could sharpen a 1953 Packard bumper with the stick they provide with the machine. All you want to do to the back of the edge is to remove any burr, you are not sharpening anything.  If you can't get the hone into the knife or it causes some trepidation, tie the hone to a stick (the hone I referenced is 4 inches long).  The hones are inexpensive, around $6 or so.

Lastly, move the bell knife in so the edge is right next to the feed wheel.  The front portion of the feed wheel will be under the edge of the bell knife, but not touching.  Adjust the feed wheel until it skives the way you want.  I think there is a setup video by Campbell-Randall or Shoe School on youtube.  After it skives the way you want, leave it alone, or make minute adjustments as required.

Art

Thanks @Art, thanks you for taking the time to write this and respond in such depth. It has inspired confidence and hope in me about tackling this machine which, yes came with basically no instructions and is very unusual in the larger scheme of things.  My skiver is a chinese model. Im going to apply all your advice / info to getting the bell knife nice and sharp. 

 

Thanks again !

On July 14, 2016 at 8:07 PM, electrathon said:

I agree with Sonydaze. your blade is likely dull and possibly out of adjustment.  Once sharp you can make perfect skives in seconds.  The reason for the ragged edge is the knife is not cutting clean.  Take a sharpie and paint the cutting area on the bell knife.  Touch the stone to it and grind gently till the sharpie mark is cleaned off.  You may need to roll the burr off the inside of the bell with a round dowel too.  My skiver chewed leather when I got it, learned how to sharpen it and it works well now.

Thanks @electrathon for the advice and words of encouragement !!!! Good to hear other people have had teething problems too !

On July 14, 2016 at 7:22 PM, Ferg said:

Get yourself a piece of at least 1/4" thick glass. Mine is round and probably 18" in diameter. Edge needs to be ground so you don't get cut on the edges. Lay the leather piece you wish to skive upside down on the glass, holding it with left/right hand. Watch the blade, they need to be very sharp and they will cut a finger in the blink of an eye.

If you have a round knife or skiving blade, allow the edge of the knife to ride on the surface of the glass. Other edge of blade should be held so it cuts an angled skive on the leather.

It takes a little practice but you can get very good at it. I can skive by hand faster than I can with the powered skiver and I don't need to throw anything away.

In the photo I have the leather on my piece of glass, the right edge of the knife is resting on the glass.

Thanks @Ferg, must give this a go ! Will report back when i do !

[Sonydaze]

On 7/19/2016 at 3:55 AM, SonderingSusan said:

Thanks  @Sonydaze for the advice is very helpful!  Yes it has been so hard to get to grips with the skiving machine and learn what adjustments do and they affect the outcome . So thanks for the advice about the position of the cutting edge ! And all the other advice / encouragement ! I think my problem was that i wasn't sharpening the bell knife at the right place. I reached in and moved the grinding stone on with my hand and it seemed to make better contact with the bell knife and give a better sharpen. It seems the only way i can move the grinding stone is manually , is this correct procedure?

Thanks again,

S

You shouldn't need to push the grinding wheel over with your hand.  See my picture...the leaver on the far right goes to the lower position to drive the grind stone. The knurled knob, that I put the arrow over, turns counterclockwise to engage the grindstone to the drum. Turn it slowly until you get sparks, I like to lightly engage it. When finished sharpening, turn the knob clockwise so it doesn't quite touch the drum and move the lever back to the top position.  One other thing that I found helpful is I polished the contact areas of my presser feet to a mirror finish, the topside of the leather slides under them easier.

Edited July 20, 2016 by Sonydaze

[electrathon]

4 hours ago, Sonydaze said:

  One other thing that I found helpful is I polished the contact areas of my presser feet to a mirror finish, the topside of the leather slides under them easier.

That is a great idea.

[Art]

5 hours ago, Sonydaze said:

 One other thing that I found helpful is I polished the contact areas of my presser feet to a mirror finish, the topside of the leather slides under them easier.

For those of us who have run a couple of miles of leather through one of these things, this is probably already the case, at least on the one presser foot we use all the time; does anyone use the other ones?  We had/have (if you can find it you are a better, or more tenacious person than anyone here is) an old Consew that looked like it had a chrome plated foot on the contact side.  Judging by the way the bearings and clutch rattled, you could probably go coast to coast with the length of leather it had eaten.  Of course, we bought it second hand and replaced only the worn down bell knife.  It was quiet enough that it was always left running.  It had ball or needle bearings, most of them (even the Chinese ones) do.

Art

[Sonydaze]

13 hours ago, Art said:

For those of us who have run a couple of miles of leather through one of these things, this is probably already the case, at least on the one presser foot we use all the time; does anyone use the other ones?  We had/have (if you can find it you are a better, or more tenacious person than anyone here is) an old Consew that looked like it had a chrome plated foot on the contact side.  Judging by the way the bearings and clutch rattled, you could probably go coast to coast with the length of leather it had eaten.  Of course, we bought it second hand and replaced only the worn down bell knife.  It was quiet enough that it was always left running.  It had ball or needle bearings, most of them (even the Chinese ones) do.

Art

Mine would very likely be polished with use by now, but polishing the feet did help with feeding when I was going though my teething problems with figuring out how to sharpen/adjust the skiver.  The Chinese makers will never be accused of over finessing their products.   

Regarding the other feet, I use the straight presser foot frequently.  We use the drum skiver a lot to skive/bevel the buckle fold over area on straps.  After skiving the strap ends we change to the straight presser foot to bevel the end of the straps.  Setup is a bit concise but you can bevel the ends as fast as you can feed them.  It is faster and does a cleaner bevel than a knife type skiver (as well as re-sharpening is easy peasy)

[Fat Dog Leather]

Thank you all for the words of wisdom. I have had a love hate relationship with my skiver. However I do believe after reading this I must be more thorough with sharpening my knife. 

Appreciate the advice! 

 

[SonderingSusan]

Hey @Art

You seem to be a bit of a skiving machine master on this thread. 

 

I was wondering which loot your use for the thin leathers and which foot you use for thicker leathers?

 

I got two feet with my skiing machine, one is 50 mm and longer , the other is shorter in foot length and a little chunkier. I was using the 50 mm for all the time. I am now wondering which foot is better for thinner leather. 

 

Thanks again ,

Ann

[Art]

Ann,

The longer foot can do a wider skive, but you don't have to use all of it.  With a well adjusted machine, either foot will do the job although the wider foot might feed a little better due to bigger contact area.  If having feed problems, a steel bottom feed roller is sometimes necessary; seems much more effective for veg tan.

Skiving machines are really adjustment sensitive, most factories leave them set-up for one operation and just tweak those adjustments as necessary.  All that said, you have to try it and run some leather through it to see which foot is best.  This is the best non-answer I can give, but I am far from an expert on these things.

Art

[SonderingSusan]

Thanks @Art,

 

And just for reference, which foot do you use for thinner leather? I'm trying out the smaller thicker foot now and finding it seems to respond well to thinner leather, but also to thicker leather so I'm a little confused?

 

Thanks again for your answer, although you claim not to be an expert , you seem to have more information on these things than most people and i appreciate you taking the time to share with a learner. "L" Hehe,

 

Thanks ,

S

[Art]

I use the long foot that follows the contour of the bell knife.  I never change feet, and the best reason is that I probably couldn't find the other feet that came with the Consew (which is the only bottom feed I have).  On the top and bottom feed (which is used the most) there's only one foot unless we make a special one, which has never been needed.

Art

[TheGr8Mattsby]

I didn't read everything written in this thread, but I work exclusively with chrome tanned leather so here are my thoughts.

First of all, the make/quality of the machine is definitely going to make a difference in regards to accuracy and ease of use. The problem with most of the cheaply made skivers is that the blade and the feedwheel run on one motor, so if you want the blade to turn fast (which it needs to in order to cut), the feed roll also must move fast. In this case, you sacrifice control.

On the higher end machines (Fortuna, FAV, etc.) the blade and the feed roll run on separate motors, so it is possible to slow the feed roll down to a crawl while the blade spins fast, allowing you maximum control while skiving.

Having said that, it is still certainly possible to get good results with a less expensive skiver, however the machine has to be well adjusted and the blade needs to be very sharp.

Myself, I sharpen the blade every single time I use my machine.

One thing you're going to want to remember is that when you sharpen your blade, you want to bring the knife to the exact same place every time. I have found that an optimal place for sharpening to bring your knife is 1cm from the leading edge. That means you're going to move your knife almost as far to the left as possible, so that there is only 1cm from the left edge of the machine. I imagine you may have screwed up your knife quite a bit, so it may take a while of sharpening at this position to rectify it. Every time you sharpen after that you're going to want to make sure you bring the knife to the same place.

Having been through this a year ago, if you are wanting to split leather (as opposed to skive) you cannot use a cheaper machine.

For my work I need to split, and having wasted more than a few skins, if you want to use the machine to split, you're going to need a higher end brand with separate motors for the feed roll and knife and which is presumably also more precise and well balanced to start.

Hope that helps

[RockyAussie]

Note below pic shows the feed stone is near to level with the bell edge. If the gap on yours is too large a gap at the front you will get what your pic shows. If you have the front of your presser foot to much angled down at the front you may also be able to get this to happen but as I've said before some pictures close up of the machine would help anyone to see the problem better. These are a machine with a lot of adjustable parts and take a few years to master well and without knowing the machine and how you have it set up we would all be guessing here for end-um.