V-Grooves

[RobM]

I've posted about this problem before, so apologies for asking again.

I can successfully do a v-groove for those smaller mounts, but I keep struggling with this one which is (by no means massive) about 450mm long. The problem is that the gradient doesn't seem to be maintained beyond the initial part of the cut.

I've tried to show the effect on what is admittedly not the best pic, but the result is that the width of groove narrows as the cut goes on.

Has anyone else dealt with this? Perhaps the length means the card is somehow lifting or something, and that's why it's an issue on the longer cuts?

[Rainbow]

I can't answer the question, sorry, but I'm interested to know which board it is.

[prospero]

Are you using a manual cutter and using the 'shave the dropout' method? If so what make of cutter?

I have a C&H and you have to ensure the guide bar is exactly parallel to the cutting bar.
On mine there is a adjustable stop for V-grooves but to make certain I have a small drill that
serves as a feeler gauge so you can check the far end.

Another tip. When shaving the dropout start the cut a inch or two back and follow through.

[Gesso&Bole]

Hi Rob

Hope you are well. Not certain what is going on here, but my thoughts would be to check the following.

1) Is the blade depth set correctly? It should only just mark the slipmat as you cut. If it is set too deep it may be flexing.
2) Are you using a new(ish) piece of board as an slipmat? If not your blade may be following previous cut lines (probably blade set a bit deep too if this is happening)
3) What board are you using? I know you have a selection of boards you got from a retired framer - they come from a number of manufacturers, and are all slightly different thicknesses - does this problem occur on a every board? (this too could mean your blade depth was set perfectly for one board, but not for another).
4) Is your mount cutter perfectly flat on the surface? Test this by cutting a normal bevel cut, with a new slipmat, and check if the surface cut into the slipmat varies in depth.
4) Have you got the mount cutter at a comfortable height, with sufficient space to stand comfortably so you can exert even pressure on the cutter head as you go through the longer cuts.

[David]

It's difficult to say, but agree with all the above, I would also add:

Which mount cutter are you using? If its a Fletcher you can apply a slight pressure to the clamping arm while cutting, for a Keencut do not apply any pressure to the clamping arm.

Always use a new blade, a blunt one may drag the board slightly if it isn't clamped enough.

If you have a Keencut use a single edged blade especially for the return bevel on the fall out, it will give a much better cut.

Hope something works.

David.

[RobM]

I can't answer the question, sorry, but I'm interested to know which board it is.

I believe it's Centred Black solid Core - SB03.

[RobM]

Hi Rob

Hope you are well. Not certain what is going on here, but my thoughts would be to check the following.

1) Is the blade depth set correctly? It should only just mark the slipmat as you cut. If it is set too deep it may be flexing.
2) Are you using a new(ish) piece of board as an slipmat? If not your blade may be following previous cut lines (probably blade set a bit deep too if this is happening)
3) What board are you using? I know you have a selection of boards you got from a retired framer - they come from a number of manufacturers, and are all slightly different thicknesses - does this problem occur on a every board? (this too could mean your blade depth was set perfectly for one board, but not for another).
4) Is your mount cutter perfectly flat on the surface? Test this by cutting a normal bevel cut, with a new slipmat, and check if the surface cut into the slipmat varies in depth.
4) Have you got the mount cutter at a comfortable height, with sufficient space to stand comfortably so you can exert even pressure on the cutter head as you go through the longer cuts.

Hi Jim,

Nice to hear from you. I've been meaning to be in touch directly actually.

So, in response:
1. The blade depth is something I've toyed with over time, which seems to involve getting the overcut and undercut settings perfect while making an effective enough cut that the window drops straight out without the need for using a further blade (more on that below, as I see that method has been mentioned - but I much prefer the completing the job on the mount cutter). I had it set at around the 3 dots marker on the cartridge, and it was marking the slipboard to what appeared 9 (subjectively) to be not too deep.
2. I try to constantly rotate new slip mats, mainly to avoid hitting previous cutlines (or at least move them to avoid the lines I've already cut.
3. I'm actually trying this on a new board - Centrado Black core, which seems to be about 2-3mm thick like most others I've used, and yet does seem a bit more rigid than most. Looking again at the Centrado catalogue, I cannot see a micron rating for it.
4. I must admit, I hadn't checked this (and I recall you mentioning it when you were here!) so I'll do this next.
5. I think I have, though I can see why it might have looked a bit crammed in when you saw it in this snug workspace. I'll check this again now, as it could well be that I've fallen foul of this more fundamental issue.

Thanks Jim.

[RobM]

It's difficult to say, but agree with all the above, I would also add:

Which mount cutter are you using? If its a Fletcher you can apply a slight pressure to the clamping arm while cutting, for a Keencut do not apply any pressure to the clamping arm.

Always use a new blade, a blunt one may drag the board slightly if it isn't clamped enough.

If you have a Keencut use a single edged blade especially for the return bevel on the fall out, it will give a much better cut.

Hope something works.

David.

Hi David,

I'm using an Ultima Futura. When you say clamping arm, do you mean the black handle used for lifting the clamp? If so, you might be onto something...I tend to hold on to this when doing the cuts.

I am trying to replace blades more often, but there's a possibility I haven't done this quite enough.

Thanks David.

[RobM]

Are you using a manual cutter and using the 'shave the dropout' method? If so what make of cutter?

I have a C&H and you have to ensure the guide bar is exactly parallel to the cutting bar.
On mine there is a adjustable stop for V-grooves but to make certain I have a small drill that
serves as a feeler gauge so you can check the far end.

Another tip. When shaving the dropout start the cut a inch or two back and follow through.

Hi Prospero,

I'm using an Ultimat Futura. I do prefer the idea of cutting the mount so that the window just drops out. I find that taking a razor to finish the job always looks a little less clean (at least when I do it - I might not have the touch for it yet). That said, your tip about starting an inch or two back could be what I have been missing.

Thanks Prospero.

[RobM]

Hi Jim,

Nice to hear from you. I've been meaning to be in touch directly actually.

So, in response:
1. The blade depth is something I've toyed with over time, which seems to involve getting the overcut and undercut settings perfect while making an effective enough cut that the window drops straight out without the need for using a further blade (more on that below, as I see that method has been mentioned - but I much prefer the completing the job on the mount cutter). I had it set at around the 3 dots marker on the cartridge, and it was marking the slipboard to what appeared 9 (subjectively) to be not too deep.
2. I try to constantly rotate new slip mats, mainly to avoid hitting previous cutlines (or at least move them to avoid the lines I've already cut.
3. I'm actually trying this on a new board - Centrado Black core, which seems to be about 2-3mm thick like most others I've used, and yet does seem a bit more rigid than most. Looking again at the Centrado catalogue, I cannot see a micron rating for it.
4. I must admit, I hadn't checked this (and I recall you mentioning it when you were here!) so I'll do this next.
5. I think I have, though I can see why it might have looked a bit crammed in when you saw it in this snug workspace. I'll check this again now, as it could well be that I've fallen foul of this more fundamental issue.

Thanks Jim.

Actually, I meant the 4 dots line on the blade cartridge.

[David]

Especially on V grooves I always use a new blade, even if I put the old blade back in for regular mount cutting if it still has some life left in it.

It's OK to rest on the little handle for lifting the main clamping/cutting bar. I was referring to the main lifting handle that runs the length of the machine, if you put too much pressure on it, it can bow, very slightly, the shaft with the cutting head on it.

[RobM]

Especially on V grooves I always use a new blade, even if I put the old blade back in for regular mount cutting if it still has some life left in it.

It's OK to rest on the little handle for lifting the main clamping/cutting bar. I was referring to the main lifting handle that runs the length of the machine, if you put too much pressure on it, it can bow, very slightly, the shaft with the cutting head on it.

I think I need to completely normalise using a new blade, especially for V grooves.

Ah, I was actually talking about the main lifting handle. I may well have been exerting weight on it, so another thing to be mindful of, going forward.

[prospero]

I'm using an Ultimat Futura. I do prefer the idea of cutting the mount so that the window just drops out. I find that taking a razor to finish the job always looks a little less clean (at least when I do it - I might not have the touch for it yet). That said, your tip about starting an inch or two back could be what I have been missing.

The most you usually have to do is run your finger along the dropout after it has been shaved to take off any fluffy bits. Because the cut is unsupported you don't get a 'clean' cut. Be extremely careful not to knock the corners of the shaved dropout.