Cutting holes

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jcoldon
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Cutting holes

Post by jcoldon »

i figured i mention the cutting holes . Since lately there lot of discussion about hole speeds.
like the other day Jim colt recommended when cutting 3/16 and 3/8 holes slow down to 60 percent on hole use 45 amp nozzle

so i say it would be nice if acorn could get a setting for holes size 2 inch and down setting keef with or size setting and speed
Mabe call the setting true hole with setting keef one could override the main dimeter setting in the drawing so no more drawing over size compensation . Lynix guys pushing for this also right now no one has this option in on screen control settings

i know sheet cam can do the separate fix for now on feed rates . but require repost for feed changes

just my input
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Re: Cutting holes

Post by cnckeith »

thanks for posting!
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
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ShawnM
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Re: Cutting holes

Post by ShawnM »

Do you really need to slow down to 60% on a 2" hole? I cut some parts yesterday with four 9/16" holes and I cut them at book speeds. 1/4" plate, 45A at 48 IPM and they are near perfect. Precision smoothing and THC were both ON. I have wondered at what diameter does Jim recommend you start to slow down at. A 2" hole to me is HUGE.

I thought SheetCam could do different feed rate overrides for different vectors.

Here's a pic of the part I cut and the bolt fits perfect in each hole with just enough wiggle room.

https://photos.app.goo.gl/Rb9N5ULcvQ4mpFk57
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Re: Cutting holes

Post by repauli1 »

Those holes look great!
ShawnM
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Re: Cutting holes

Post by ShawnM »

Yes, I was even surprised how well they looked cutting at book speeds and feeds (profile manager matched the Hypertherm book) and with THC on. Each one fell out at each cut unless it was sitting on a support rib in the water table. Parts turned out great and I'm hoping the next ones look just as good.
jcoldon
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Re: Cutting holes

Post by jcoldon »

Shawn there is no set dimeter of a hole to slow down it all depends on the table acceleration and velocity ability. i just said start at 2 inch and down
it the program . Not every table has the ability to cut perfect holes at book speeds. Most of the time running holes with thc and book speeds creates taper.
the thicker you cut the more the taper so size offset is necessary . This is all stuff Hypertherm has tested in their lab. then the operator has to apply
this to his table know what he needs to do to get good cuts .

Yes sheet cam new post has feed rates for different layers it overrides the feed rate in profile mgr . if you want the profile mgr setting you have to switch back to no feed post repost drawing .. it a fix for now till they build second feed rate in the screen with separate offset setting like keef with

My post said slow down cutting 3/8 holes not 2 inch holes in 3 /16 . the fact is small holes mostly 1.5 inch down the smaller you go will require some speed change . acorn software seams to somewhat slow down cutting holes.
But take 1/2 inch cut 5/8 hole at book speed not Gona happen 85 amp and get good cut
i already proved that with joey we did 22 ipm on that hole with very good results i found thc off was just tad better on taper was about 25 k i usually do my drawings about 25 k over for bolt holes
General rule on holes no smaller then the thickness of steel your cutting . and use the lowest amp nozzle for good cuts
Holes cut CCW outside cut CW
jcoldon
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Re: Cutting holes

Post by jcoldon »

The reason i suggested 2 inch hole setting on down. Because the software going to have to recognize holes some controllers i used that do this second speed on screen mainly for holes go buy hole size you select . I'm no programmer so it was just a suggestion .

Rember every table that diy going to have different acceleration and velocity . Not every one knows to build high acceleration table to due Hypertherm book speeds In plasma it all about acceleration and g force not to have velocity slow down . were router doesn't matter .

Shawn i looked at the holes you cut . What i see is a slight taper inside > i also see a slight dink in each inside were the lead in starts at to bottom of each hole
this is were the thc takes control of Hight based on holes have a slight different voltage reading and slightly changes the Hight after the IHS settings
i bet you turn off thc Thay be gone you have little less taper do a slight lead out to stop the dink
what is your table velocity setting are you using 1.5 in motor setting I found that setting make big difference on 1/2 plate
ShawnM
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Re: Cutting holes

Post by ShawnM »

Thanks for the input Jeff. I did see that Jim was talking about small 3/8 and 3/16 holes. I was confused about your comment of a 2" or smaller hole. I do know that cutting small holes in thick material is probably not gonna happen. There's a limit to all machines. This is where my air actuated engraver comes into play, I can simply mark the holes with the engraver and then drill them on the mill afterwards.

I agree that every machine is setup different and each can have it's own settings for accel and velocity, and even deceleration. A DIY machine with a lightweight gantry can easily have faster settings and have an advantage with plasma. A professional built machine with a gantry that is large and heavy may not be the best solution for plasma. My machine cannot have the same settings as one like yours given the construction and size of the gantry. It'll take some tweaking by the end users to find what works best for their table design and weight. I think a lighter gantry has its advantages over my ShopSabre gantry. Mine simply cannot start and stop like a lightweight machine can.

The last parts I cut, the holes have almost no taper, looking straight into the hole. It's hard to see from the pic but the left side of the hole shows the least amount to taper. If all my holes have this little taper I'd be very happy. They are slightly oversized a few thou to fit the bolt. I didn't do any overcut or lead out but will try on the next part. The little dink in the wall is no issue but if it can be better I'll try. I'll also try and turn off THC and compare. I wonder if I can turn off and on THC on the fly with the "THC Auto" button on the VCP. If would be great if I could turn it off by pressing the button when it cuts the four holes and then turn it on with another press of the button. I know this can be done with the PP to do this automatically but a manual option for one off parts or testing would be cool.

My accel/decel settings are .4 for the X and Y axis and .3 on the Z axis if this is what you are asking. I don't know what you mean by "are you using 1.5 in motor setting I found that setting make big difference on 1/2 plate". What setting are you referring to?
jcoldon
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Re: Cutting holes

Post by jcoldon »

you can turn off the thc with a code snippet in sheet cam
you have no thc on holes and the main cut thc back on it not a post processor thing it simple g code
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