dirtymonkee

MH721 Pressure and not cutting correctly

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Please Help.

Model:MH721

Program:SCAL Pro

I am cutting circles that seem a little off. Not oval just off. The only think that makes a difference (for the good) is reducing pressure to 30g but this don’t seem to go all the way through the vinyl. At 40g it cuts but deforms the circles a little. Higher pressure makes it works.

I have tried: Different lead, different PC, changing blade length, blade speed, vinyl type, Offset and over it, new blade, different program.

Anyone have a solution.

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Try calibrating the software/cutter. I don't use SCALP but there should be a calibration procedure someplace.

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 Setting force is determined by the blade depth. Too many incorrect instructions out there say to use a credit card or post it notes. These are incorrect. You set your blade depth and force to the vinyl that you are cutting. Also make sure that you are never pulling from the vinyl roll while cutting.  Cut slow, while learning your machine. 

To start with, you should set your blade depth correctly, by taking the blade holder out of the machine, and firmly cut across a piece of scrap vinyl, you will be cutting. You should only be cutting the vinyl and barely a mark on wax paper backing, Adjust blade to get there, Then put the blade holder back in machine, and use the force of the machine to get there, same results, only cutting the vinyl and barely a mark in wax paper backing. You should barely see and feel the blade tip out of the blade holder. Regular sign vinyl is only 2-3 mil thick. You only cut with the very tip of the blade. When you think the blade is so far in the blade holder, that you think it would not even cut, that is probably correct. 

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1 hour ago, MZ SKEETER said:

 Setting force is determined by the blade depth. Too many incorrect instructions out there say to use a credit card or post it notes. These are incorrect. You set your blade depth and force to the vinyl that you are cutting. Also make sure that you are never pulling from the vinyl roll while cutting.  Cut slow, while learning your machine. 

To start with, you should set your blade depth correctly, by taking the blade holder out of the machine, and firmly cut across a piece of scrap vinyl, you will be cutting. You should only be cutting the vinyl and barely a mark on wax paper backing, Adjust blade to get there, Then put the blade holder back in machine, and use the force of the machine to get there, same results, only cutting the vinyl and barely a mark in wax paper backing. You should barely see and feel the blade tip out of the blade holder. Regular sign vinyl is only 2-3 mil thick. You only cut with the very tip of the blade. When you think the blade is so far in the blade holder, that you think it would not even cut, that is probably correct. 

Increasing force only makes it worse, decreasing improves but don’t make it all the way through. I have tried setting the blade as per your instructions but can’t seem to get it right. Please note: this is a new issue, was cutting fine a few months back.

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Could you have broken the tip off the blade?  Hard to see unless under a magnifying glass.  Also, take a good look at your teflon cutting strip, make sure no scratches, or gouges. Those will cause you problems.  You only cut with the very tip of the blade.  No mention what type of vinyl you are trying to cut. Make sure carriage head wheels are firmly down in the track.

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18 minutes ago, MZ SKEETER said:

Could you have broken the tip off the blade?  Hard to see unless under a magnifying glass.  Also, take a good look at your teflon cutting strip, make sure no scratches, or gouges. Those will cause you problems.  You only cut with the very tip of the blade.  No mention what type of vinyl you are trying to cut. Make sure carriage head wheels are firmly down in the track.

Used a new blade. Might be the strip, good shout. Can this be replaced?

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So I’m using the far left side of cutter. Never usually got his far so teflon strip is fine. Set blade as described and still nothing!

setting that pressure cuts well but distorts design.

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 you should be showing pictures, of your cuts. We can't tell what is going on.  What does the TEST cut look like? TEST right from the machine. Show the screen shots. Show your settings in your cutting software.  We are only volunteers here.  You would have to contact UScutter tech support for mechanical problems. Make sure the grit rollers set screws are tight, The belt is tight. 

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Hey there dirtymonkee, I have an idea, it's a longshot, but it happened to me.

That plastic arm retaining the bladeholder in place is fragile and can be broken by overtightening the knurled (brass) nut. You may not see it, but the piece may develop a hairline crack. This allows the blade holder to wobble, and the result is bad cuts.

Take the whole carriage arm apart (remove the hinge pin) and carefully inspect for damage.

https://uscutter.com/uscutter-mh-vinyl-cutter-replacement-parts/

 

 

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3 hours ago, MZ SKEETER said:

 you should be showing pictures, of your cuts. We can't tell what is going on.  What does the TEST cut look like? TEST right from the machine. Show the screen shots. Show your settings in your cutting software.  We are only volunteers here.  You would have to contact UScutter tech support for mechanical problems. Make sure the grit rollers set screws are tight, The belt is tight. 

I’ll see if I can get some pics another day now. I literally done every combination of everything. As soon as the force is high enough to make a nice cut it deforms circles. I did manage to alleviate a little by turning up the overcut a tad but this affected right angles. Was great(ish) for circles.

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4 hours ago, dirtymonkee said:

I’ll see if I can get some pics another day now. I literally done every combination of everything. As soon as the force is high enough to make a nice cut it deforms circles. I did manage to alleviate a little by turning up the overcut a tad but this affected right angles. Was great(ish) for circles.

overcut won't affect corners like right angles, offset will - - -  did you try adding some light oil inside your blade holder?  or even a new blade holder if you have had the plotter quite a while.    the UK Refine MH 721 seem to be a bit different than the ones that uscutter sells here - but basic function should be the same

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8 hours ago, Dakotagrafx said:

overcut won't affect corners like right angles, offset will - - -  did you try adding some light oil inside your blade holder?  or even a new blade holder if you have had the plotter quite a while.    the UK Refine MH 721 seem to be a bit different than the ones that uscutter sells here - but basic function should be the same

I’m gonna try a bit of oil later. I feel this could be the issue.perhaps the blade not turning quick enough to cut exact when more pressure is applied

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21 hours ago, MZ SKEETER said:

 you should be showing pictures, of your cuts. We can't tell what is going on.  What does the TEST cut look like? TEST right from the machine. Show the screen shots. Show your settings in your cutting software.  We are only volunteers here.  You would have to contact UScutter tech support for mechanical problems. Make sure the grit rollers set screws are tight, The belt is tight. 

Ok. So i tried adding a bit of light oil to cutter blade holder but this again didn't improve any. Here are some screen shots of the test pattern right from machine. What I am trying to cut is a circle and the Oculus (VR Headset) Logo. I have managed to get it perfect before.IMG_7846.thumb.JPG.f396ac00d30c328fcd6f8d91a29a5f20.JPGIMG_7848.thumb.JPG.8c456003f618684f092ad684cfee7d91.JPG

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 Your TEST cut straight from the machine is not good. Can you show a picture of the blade sticking out of the blade holder?   Did you ever check the belt and the grit roller screws to make sure they are tight?  Make sure the carriage head wheels are firmly down in the track.  Did you check for a crack in the carriage arm?  

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Get down eye level with the blade holder and watch is closely as it works. Is there any wobble in it? My carriage arm holes for the blade holder were not cut well and the holder would wobble and cause problems similar to what you're seeing. A cracked holder arm would cause a wobble as well.

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So. I’ve had another play this evening and have set up my camera to record the movement and recorded it on slow and found no visible wobble: carriage rollers are fine as are pinch rollers and no cracks in holder/cradle. Belt is good too.
 

lve added more photos and another test cut.

A2DAF05C-4240-4FA9-AAD4-5EBB769A8965.jpeg

360A31FC-52FA-4AFD-A958-FDEE2311B692.jpeg

567B3873-851E-4690-B26C-50EACBD24166.jpeg

9DF06C09-C92A-4520-9276-BDECCF2D5EE5.jpeg

CE770BB6-7A59-4551-A041-38878503F6BE.jpeg

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one more quick question - You haven't changed the pressure on the pinch rollers at any point have you?

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24 minutes ago, Dakotagrafx said:

one more quick question - You haven't changed the pressure on the pinch rollers at any point have you?

I have, to try to alleviate issue but changed back. This is what they are on now. Level with screw. No pressure, less or more made any difference.

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4 hours ago, dirtymonkee said:

I have, to try to alleviate issue but changed back. This is what they are on now. Level with screw. No pressure, less or more made any difference.

too many people over the years have lowered the pressure to eliminate the marks made by the pressure rollers that are totally normal and cause problems similar to yours - as the blade causes more friction than the pressure rollers the vinyl slips - kinda thought from the pictures the pressure had been lowered quite a bit. 

On yours compared to the others I have seen the spring has the top coil pulled up quite a bit - on most the spring separates evenly throughout the coils as the pressure is increased 

 

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29 minutes ago, dirtymonkee said:

So, something fundamental has changed and can’t be fixed. This is how it seems. I give up, it has me beat.

Just for troubleshooting tighten those pressure rollers a little more . . .

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23 minutes ago, Dakotagrafx said:

Just for troubleshooting tighten those pressure rollers a little more . . .

Admittedly I did see more marks In the vinyl then I am now so maybe they do need to be tighter but I have also tried this before. Will try again, my fifth day of trying to sort. I do appreciate all your help.

If all else fails can someone point me in the direction of a decent cutter? Don’t need to be as big as the 721

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8 hours ago, dirtymonkee said:

Admittedly I did see more marks In the vinyl then I am now so maybe they do need to be tighter but I have also tried this before. Will try again, my fifth day of trying to sort. I do appreciate all your help.

If all else fails can someone point me in the direction of a decent cutter? Don’t need to be as big as the 721

hoist that roll of vinyl up and put a new graphtec under it - if it doesn't need to be as big look for an new old stock ce6000-40 - haven't seen any reports on the 115" version like that but lots of issues with the new ce7000-60 since they moved production.   also not familiar with the UK market other than I know they have the graphtec, roland and summa plotters - all of which are a large step up from the refine MH -  

very little marks on the vinyl would indicate the pressure is not high enough on the rollers - the marks are normal and go away when the vinyl is installed

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6 minutes ago, Dakotagrafx said:

hoist that roll of vinyl up and put a new graphtec under it - if it doesn't need to be as big look for an new old stock ce6000-40 - haven't seen any reports on the 115" version like that but lots of issues with the new ce7000-60 since they moved production.   also not familiar with the UK market other than I know they have the graphtec, roland and summa plotters - all of which are a large step up from the refine MH -  

very little marks on the vinyl would indicate the pressure is not high enough on the rollers - the marks are normal and go away when the vinyl is installed

Thanks for help. Will adjust pressure on pinch rollers and check out the plotters you recommended.

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