Cutting glass on the Keencut 5000

[Jamesnkr]

Been meaning to post about this for a bit.

I had previously religiously followed the instructions. Put glass on cutter. Score. Press firmly at top and break it.

With a crash and a bang, the glass is broken in a lightning quick move. Or sometimes half of it breaks off and I end up with jagged splinters.

Cutting AR, I followed their instructions and put a piece of mount board behind it so as to prevent scratching. When you press firmly at the top, the mount board acts like a spring, and the cut begins to run gently down the glass, and you can push at the glass near the cut all the way down.

Well, that makes it easier! I'm surprised it's not in the instructions... which makes me wonder whether I've got the wrong end of the stick.

[Graysalchemy]

How old is the cutting wheel? They do need replacing fairly regularly depending on usage.

[Jamesnkr]

So it's supposed to go with a bang in a split second? I much prefer the gentle way...

The answer is 'I don't know.' But it leaves a nice clean line and - this way - I get a perfect cut every time.

[Graysalchemy]

You just need to stop being frightened of it. push either side in centre whilst it is on the cutter or if its little pieces of glass you can usually crack them by just snapping. If the wheel is worn then you are likely for the glass to no go along the score.

[prospero]

If you are getting splinters then there is maybe too much pressure. Try backing it off and doing quarter turns clockwise on the allen screw until it cuts clean. It should break with a gentle tap. A dab of white spirit on the wheel seems to help a bit to.

[Jamesnkr]

No, no splinters. The wheel makes a nice cut. If I use a pair of running glass pliers the process is always nice and gentle.

Using the Keencut it always seems so violent and uncontrolled. In the instructions it tells you that if the cut only runs part way then you need to push it a bit more lower down, I can't imagine ever being in a position with a part-run cut.

[prospero]

Sorry. Read it too fast.

This happens to me now and then. Never with AR glass though.
I may be that you are clamping it too tight.

To snap the score I usually give it a thump with my fist on the 'waste' side. Sometimes if you are too gentle it misbehaves. Show it who's boss.

[pepper]

Hi James, if the glass feels springy or breaks with a bang there is simply something not right with the glass or the glass wheel. First of all the glass, if you have had the same results on different supplies/batches of glass then that can quite easily be ruled out.
The wheel has to be in good condition so if it is not rotating easily or is dull it will not give you as good a score line as you may think you have. It sounds as if you have doubt about the age and history of the wheel so my advice would be to change it, if it makes no difference then perhaps one of the settings are incorrect.
There are two settings, the pressure setting is on the screw by the green label but there is also another setting which is only adjusted once when the machine is being built this is under the red label on the edge of the rotating head. This sets the position of the wheel to give you good contact on the glass surface. Contact Keencut if it looks like the wheel is not in full contact with the glass surface (although from what you say this this doesn't seem to be the problem).
My money is on the wheel condition and perhaps the pressure setting.
On my machine I can score a strip 2' long and half and inch wide then whilst it is in the machine just twist it off gently between finger and thumb from the top end.

Pep

[Jamesnkr]

Pep thanks.

I'm fairly sure that the pressure is set up correctly, as I had a good play with that, and the wheel touches the glass correctly, and it's nothing to do with the different types of glass. I took off a strip 3mm wide and 60cm long yesterday, using running pliers after scoring on the Keencut, so I'm fairly confident that it's all working well on the scoring front.

Twisting off gently is not what the manual tells you to do! The manual says:

To break the glass, apply firm pressure to the left hand side of the score line adjacent to the top
edge of the glass.
NB: On large sheets of glass the break may only go part way down the score line, press again near the end of the
break to continue it.
Never score the same line twice.
We recommend the use of nibbling pliers for the removal of amounts less than 5mm (1”)

My only gripe is with the "apply firm pressure to the left hand side of the score line adjacent to the top edge of the glass" which in my book means push hard where 'x' marks the spot

keen.JPG (44.62 KiB) Viewed 14423 times

It appears that neither you nor GA is doing that. You "just twist it off gently between finger and thumb from the top end." GA pushes it in the centre. Prospero is giving it a thump at the top in accordance with the instructions.

Glass cutting is normally an elegant and gentle activity. The traditional glass merchant's approach is to pick up the two sides and tear it as gently as you would tear a bolt of fine silk cloth. The Keencut bang as the glass hits the back board on the left side is neither gentle nor elegant. You've lost control of the crack.

So when cutting AR glass, as instructed on the packet I used some mountboard to prevent scratches. At which point you can't really bang it. You need only give it a gentle push, supported by the mountboard, and the crack will run slowly and gently.

[Graysalchemy]

I push it both sides, sometimes with a thump, if it's a thin strip then I put it on the bench and snap from one end. Took a 3mm slither of today by just gently snapping with my fingers and thumb, came off in one gie no jagged edges.

[prospero]

I bang it in the middle.

[GeoSpectrum]

I had a similar problem recently and it was a pressure problem. A small adjustment (increase) in pressure and the glass snaps with practically no effort.

[Graysalchemy]

I fitted a new cutting wheel which didn't sit right as a result glass wasn't cutting and snapping was a nightmare. Took me six weeks to realise the wheel was carp I was ready to buy a new cutter it was that bad . Anyway new wheel and it works like a treat again

[IFGL]

Pep you are bang on, I could not have put it better, the only thing, I could add, is to make sure the Teflon bearings are correctly adjusted, if they are not it will throw out your other adjustments.

[IFGL]

By the way I push around where your x is.

[Trinity]

I'm definitely on the short sharp hit around the middle and it goes like a dream. I use pliers for the minute slivers but with mixed success, I cannot seem to snap it in one go however I try, must be me

[caro]

I score and cut glass by hand but the principles are the same, my two pennyworth is: don't forget glass cutting and snapping goes wrong and is affected by the cold.

[Graysalchemy]

Well I constantly cut in the cold and don't have any problems even when conditions Are zero in the workshop. All the problems I have are from cutting wheels which are dull.

[Whitewater Gallery]

Jamesnkr, we had our 5000 from new Nov 2014, I would guess we cut an average of 3 frames a day through the year and I had to replace the wheel after 10 months. Before replacing the cut looked just the same as always but there was more resistance to the push to snap it and (we only use AR glass) it was regularly starting to crack the good bit. My advice if in doubt change it, I keep a spare anyway just in case.

On replacing the wheel it costs like a dream and I engage the wheel with less pressure (5 clicks as we have a piece of mount board behind the AR glass to avoid scratching) and will increase the pressure as the wheel ages as we did before.

2 hands a a good positive push does for me!

[pepper]

There seems to be a number of different ways various people are breaking the glass and if the score line is good then any push, twist, thump or press will concentrate the glasses distortion around the score line to produce a clean break. Personally I press at the top where James' X is because should anything go wrong and the glass do something unexpected then my hand is at the top of the glass and out of danger of falling fractured glass. The fact that it could chop my toes off is another matter

I strongly recommend forking out a few extra pounds on another wheel and then you can compare.

As a by-line, many years ago I was shown microscopic photographs by someone who had been in the glass industry all their life. These were pictures of the glass surface that have been score using different pressures and different wheel angles. What he explained to me is that for a perfect score line to be made it relies on three things; the angle of the wheel with respect to the thickness of the glass, the pressure on the wheel and the quality of the wheel (be that the material it is made from, how well it is ground or if it is dull through use). If any of these things are not correct it will either not score consistently or if it does produce what looks like a consistent score line it may in reality not be a good one.
He went on to explain that a good score line produces a single neat channel in the surface of the glass so the distortion given to it when pressed knows exactly the line to break down. If the score line is bad it will look like a minute version of a ploughed trough through a field with minute fissures breaking off left and right alongside the main score line. This means that when the glass is pressed it is unsure where to break and rather than concentrating the stress around a single score line it dilutes the stress around the thousands of small fissures until you push hard enough to help the glass make its mind up where to break.
I hope the above makes some sense, but when it was explained to me by Ronnie Berlyne 20 odd years ago it helped my understanding of glass no end. I just wish I had a copy of the photographs now to pass on!
Pep