what's the cause of a blurry litho

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drrobin
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what's the cause of a blurry litho

Post by drrobin »

I finished my first litho and it looks good except it's a little blurry. Having bit problems (user issues) and finally just used my 1/8 inch bn which I know doesn't give the detail, but would that cause it to look blurry? Thanks!!! Just thankful to accomplish it! Tutorial really wasn't accurate...

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Xxray
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Re: what's the cause of a blurry litho

Post by Xxray »

Yes, too large a bit and you lose clarity & detail.
For an average 8x10, I use a 1/32 bit, wouldn't think of using anything less than 1/16th. Only way a 1/8 bit could get good detail is if the project was substantially larger, like 14x18 or so.
Also make sure you check the box "convert light/dark areas", if you don't it will come out as a negative which can have a blurry effect.
Doug

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Rcnewcomb
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Re: what's the cause of a blurry litho

Post by Rcnewcomb »

Look at it with the carved side facing towards you.
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop

drrobin
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Re: what's the cause of a blurry litho

Post by drrobin »

Thanks! RCNewcomb it dawned on me later that I had it the wrong way:-) So it looks pretty good for my first try-at least I'm happy with it! I have a 1/16 bn but it wouldn't cut down deep enough so I have a simple tool question. It's a 1/16 2 flute 3/16 cut length...I'm posting what I have set when I select the tool-will that work? Sounds like I should be able to do it in one pass based on everyone's experience so I set it for 0.2 which is what I've done that's worked best for me.
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Xxray
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Re: what's the cause of a blurry litho

Post by Xxray »

It can be unnerving to watch the slender finish tool makes its 1st pass, especially if it is a white [deep] area. The 1st pass 100% of the tool is cutting into the material, after that its much less. More likely the corian will fracture than the bit, or come unset depending on your hold down method.
This scenario is unlikely but happens eventually - To avoid it completely, just set a line angle of 45. This has no effect on time or quality, it will start the project in a corner and will avoid that long 1st cut all together.
Doug

drrobin
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Re: what's the cause of a blurry litho

Post by drrobin »

Thanks Xxray! Do the settings I've assigned to my 0.0625 ballnose make sense? Am I asking the bit to do something it's not capable of because if it's size? Robin

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Xxray
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Re: what's the cause of a blurry litho

Post by Xxray »

I usually go with the tool defaults, might try boosting up feed to 200 ipm or so ,,, Though with 3D it pretty much goes at 1 speed, but 75 is pretty slow.
So long as it makes its line sin 1 pass you should be good [ie: if you had you depth of cut set to .22 and tool was set to .20, it would make 2 passes so it would be much better to set it to .22]
Doug

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Re: what's the cause of a blurry litho

Post by drrobin »

Thanks, I may try to go with a 150 ipm next time and see:-) I love that I'm able to understand now what you mean when you say it would take 2 passes to do a .22 with a .20 setting! In the beginning I wouldn't have understood that so happy that I'm making progress in my learning! All because of the support on this forum!! Thanks everyone, Robin

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scottp55
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Re: what's the cause of a blurry litho

Post by scottp55 »

Robin,
Just in case you hadn't seen it.
http://www.shopbotblog.com/2008/03/a-ra ... rformance/
Especially check the section "my approach to VR settings" when Brady talks about MS for 3D as that's sort of what you're doing with PVC and you want your Z speed up a little I think to closer match your X,Y.
Don't use PVC, so what do I know, but pretty good luck in 3D wood using 50-100% Z speed of my X,Y speeds on Desktop.
Saw your litho and think it's great for that size with a 1/16" and a first try.
Nice to see you working through it! :)
scott
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Xxray
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Re: what's the cause of a blurry litho

Post by Xxray »

drrobin wrote:Thanks, I may try to go with a 150 ipm next time and see:-) I love that I'm able to understand now what you mean when you say it would take 2 passes to do a .22 with a .20 setting! In the beginning I wouldn't have understood that so happy that I'm making progress in my learning! All because of the support on this forum!! Thanks everyone, Robin
Its all a process for everyone, trial & error + forum = progress.
Took me a while to figure that out when I first started doing lithos, I was watching the cut and was taken aback that it was making 2 passes for each line, obviously that right there is going to double the cut time, so I dived into the settings and figured it out.
On the other hand, thats not a rule, really an exception. Especially with roughing wood or thick plexiglas, you have to go with small [.125] passes else you'll stress the bit/machine/material too much and something will fail. Corian is actually pretty forgiving compared to alot of other materials.
Doug

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Re: what's the cause of a blurry litho

Post by drrobin »

Thanks again for help everyone... Scott, thanks for the link. When I read through the info, the MS he refers to would be to change the VR fill in sheet to settings i.e. 3,2 - 3 being the xy speed and 2 being the z ramp speed or is this a ratio? The defaults are ".4" so that's quite a difference and I may not understand. I would like to improve on the clarity and can see how having the z speed could influence this. Thanks, Robin

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scottp55
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Re: what's the cause of a blurry litho

Post by scottp55 »

Robin,
Shopbot's a little different as your SB3 comes default in IPS (Inch Per Second) usually for MS (Move Speed).
A fairly common standard shorthand for Feeds/Speeds is to say "1.2,.5,16K" for instance, That would mean 1.2 is IPS for X,Y Move speeds, .5 IPS for Z(plunge), and 16,000 RPM.
That's the settings in your Vectric toolpaths, NOT in VR.
TJ in his 3D's for instance runs his 3D's with both settings matched(say 2,2 or 3,3) because speed is limited by your slowest axis.
I personally haven't messed with VR much as it's almost all small proto's for me, BUT have printed out everything I can find and will be changing mine for 3D and tiny VCarves after reading the pluses.
http://www.talkshopbot.com/forum/showth ... via-Tuning
For Dished models with no roughing pass I have gone 1,1/1.5,1/2,1/ and 2,2 and kinda like 1.5,1 for a tiny .125"30degree engraving bit in Bloodwood.
Only useful if you start at the corner with that one initial plunge
I'd listen to Xxray as he's got PVC and cuts nice Plexi and Corian!(pretty useful guy to have around:)
Just thought you might be interested in speeding things up once you find quality you like.
Think your 32'nd will help you with the detail you want.
Shouldn't have opened my big mouth on PVC :)
scott
I've learned my lesson well. You can't please everyone,so you have to please yourself
R.N.

drrobin
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Re: what's the cause of a blurry litho

Post by drrobin »

:-) thanks for info. What you say makes sense. And all information Helps bring clarity to what I'm doing whether I use it or not. Appreciate the explanation. Thanks, Robin

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