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how much pressure/force should a cut take?

Posted by oldsailorsknives 
how much pressure/force should a cut take?
September 25, 2018 01:27PM
Trying to get some base data to do testing. I am using a basic digital postage scale. I added cutting board and item to cut, then zeroed. To slice an onion in half, I saw max weight of 6 pounds. Does this sound reasonable? Is this pressure or force?
once i have some base line numbers, I want to apply the same weight using different cutting boards and see if board material effects sharpness. Test would be edge against board with chosen weight, move blade back and forth several inches ?? times. The test is to see if there is measurable difference in sharpness after cutting on PP, HDPE, face grain wood, edge grain wood, and edge grain wood. Blade would be mounted in a vise and moved on a linear rail so you would be looking at a 'pure'(no side forces) pull cut.
sound like a reasonable test or am i chasing unicorns?

scott
[www.etsy.com]
Re: how much pressure/force should a cut take?
September 25, 2018 02:53PM
should say end grain as last choice.

scott
[www.etsy.com]
Re: how much pressure/force should a cut take?
September 25, 2018 07:48PM
In order to make sense out of these numbers you need reference points other blades, because vegetables are really prone to variation and technique makes a huge difference. What I would suggest is keeping one of your knives as a reference and you can always use that to benchmark others.

The other thing to consider is what you are giving up. I have a number of knives which can cut a potato and a lot of vegetables and they won't even move the scale so they are < 1 lbs. But they are very thin stock, close to zero ground, < 10 dps at the edge which is almost a micro bevel. I would not even cut some very hard vegetables with them as the edge would get damaged on some harder stalks (squashes and such).
Re: how much pressure/force should a cut take?
September 25, 2018 08:14PM
thanks for replying Cliff. just looking for a starting point. so I place the board over the knife then add a weight. would that be a realistic way to simulate the force one applies while cutting? i also have blades that require a light touch to cut, part of the problem was cutting on a board on a scale and trying not to add any additional weight except the force behind the blade.

scott
[www.etsy.com]
Re: how much pressure/force should a cut take?
September 28, 2018 06:52AM
In the european union we have some nonsense hygienic regulation for the restaurants
same as any food processing manufacturers. Only certain certified plastic grades are allowed to be used
for boards. (people used wood for thousands of years and everyone
uses at home anyway with no harmful efects - ridiculous)

Friend chef limits use of a knife I made for him at work because at high sharpness
at some 25deg inclusive it cuts relatively deeply into the cutting board while rocking.
Plastic board is easier to cut into than hard wood but its very resilient so makes
thin edge to suffer from lateral forces always it happens..

Slight deviation from straight trajectory (inavoidable) while rocking on a plastic board makes
terrible sounds when the thin edge "jumps" out of the groove that was cut by the edge into the surface..

High sharpness of the knife belly is lost realtively fast (the most rocking - and steel screaming)

Scott, I assume at the high sharpness the differeces will be tremendous between
plastic and wood and could be observed after first few tens of cuts..

Interesting idea, I would be curious to see a difference between cork and hard woods..
No idea what would happen..
Re: how much pressure/force should a cut take?
October 01, 2018 06:59PM
Quote
oldsailorsknives
thanks for replying Cliff. just looking for a starting point. so I place the board over the knife then add a weight. would that be a realistic way to simulate the force one applies while cutting?

Yes.

I did a lot of cutting early on using a bathroom scale to get some idea of the forces. I was quickly surprised how the same "kind" of knives could easily vary from 1 to 20 lbs on various vegetables. The thing to take about is as you get very optomized the knife gets kind of very particular. A knife which cuts through vegtables in <1 lbs could very likely just get mangled unless you use it carefully.
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