How long would computer mountcutter blades normally last?

[boscawen46]

Hi,
As per heading , how long do people generally find their blades last cutting mounts on a computerised mountcutter. I am cutting full sheets of mountboard with between 9 -15 mounts in a nest either 12" x 10" or 10" x 8". The blade is cutting the window out ( between 8" x 6" and 5" x 3") and also the outside cut of each mount.
After about 30 mounts I have noticed that the cut is not not quite going through on the window cut and when I check the blade it is obvious that the tip of the blade is worn so that there is no sharp point. I have the "plunge" of the blade set up in software so that it only just scores the sacrificial underlay board and so it is not hitting the bed of the cutter itself.
Is this type of wear normal after the numbers and size of mounts I have mentioned and would the tip normally flatten off slightly like that?
I have found that I can prolong the life of each blade and cut more mounts with it by increasing the depth of plunge minutely once it has worn slightly.
Any advice welcome
Thanks

[Ed209]

Sorry can’t give the answer to your question but think you have probably answered it yourself.
I think it would be a good idea if the software recorded the distance you actually cut allowing for the materials selected then you could base your decisions on that.

[YPF]

By my calculation after cutting 30 mounts the blade will have plunged 240 times (4 for each aperture and 4 for each outside cut x 30).

On my CMC I expect to change the blade after no more than 120 plunges (less if I’m cutting thicker boards).

I reckon the cost of a blade is negligible when compared to ruining any number of mounts. I’m sure I read somewhere (probably on the US framers forum) that somebody tried to sharpen CMC blades just to get a bit extra out of them.

[boscawen46]

Thanks for your replies. I guess, thinking about it, that is quite a lot of plunges/cuts for the blade and it only works out at about 1.5 pence per mount taking the price of the blades into account ! Pretty good really.

[David]

Sounds about right to me. Always amazes me how abrasive mountboard can be. Wear and number of cuts seems normal and what I would expect.

[Steve N]

Are you using new blades, as I have found that the latest ones I have purchased, don't seem to last very long, might be a bad batch
When cutting a full sheets of multiple mounts , I tend to move (in the software ) the array around so not cutting in the same place all the time, which tends to make the bottom of the mount bend into the pervious cuts, thus not cutting through
What mountcard are you using

[grahamdown]

if cutting lots of cuts in one go are you loosing any air pressure and then not driving the blade with sufficient pressure? i have the problem if i forget to up the pressure when cutting 3.5mm boards.

[boscawen46]

Hi
thanks for your replies. I ran the diagnostics software for the machine ( Gunnar F1 hybrid) that gave advice on how to calibrate the cutting head so that it only just cut through the mountboard (1400 microns) . This was a very accurate process involving sheets of paper !
After doing this the blade has far less wear on it because it is not cutting the underboard so deeply it literally just scores the under surface.
This morning I cut 90 12" x 10" double window mounts including the outer cuts and only then did the blade not quite make it through the bevels were clean too.
Good result I think !

[Ade704]

We have the F1 too and have had similar problems. Common causes are:

1 - dropping the plastic case that holds the new blades. They are very delicate and a shock can weaken the tips, making them break early
2 - getting a bad batch of mountboard. If it has grit in it, this can cause the blades to wear out early
3 - not fine-tuning the depth using the 5 sheets of paper. You need to do this for each profile too by the way
4 - Letting the pressure drop too much, which can happen on multiple runs. You might want to let some air out of your compressor to force it to kick in and re-pressurise if it isn't doing it early enough
5 - catching the tip of the blade on the way into the holder