What's causing this?

[dhunt]

We have to cut something like 100-200 of these little box things
-they're about 4 x 6 ins. in size.. out of 1.75 ins. thick Mahogany.
We're using a 0.5 in. spiral upcut bit by Amana.


I'm getting this annoying little groove happening in all six passes
(see attached pics below)

The flaw is happening on only one 6 in. side of the boxes, as the machine cuts in Y
going out from my nearby side of the table --but not on the other side, coming back in.

I've had a look at the racks/pinions,gear cogs
and even cleaned the center grooves of the wheels -the rails seem OK if a little worn.

I've cut several of these boxes across the table in several different X-positions
so I feel it's something going on in Y? :confused:

_______________________________
Could it be a Z problem?
Could it be a slightly-loose router in the frame?
One of our two hose clamps securing the variable-speed 3.5 hp Porter-Cable is ..ah... in need of replacement
but why is it happening in just this one spot, on one side only?


I've lined up a few of the boxes but, as you can see,
it's not happening in precisely the same place along that 6 inch run in Y.

What gives? Ideas?

[steve_g]

Were these all cut from the same file? It looks like a dwell mark from the bit plunging and retreating. Try using a lead in and out. However, if they are cut from the same file that would not explain the changing position of the marks.

Steve

[dhunt]

Were these all cut from the same file?
It looks like a dwell mark from the bit plunging and retreating.
Try using a lead in and out.
However, if they are cut from the same file
that would not explain the changing position of the marks.
All cut from the same file!
I know what you mean about a dwell-mark, but no it's not that..

The bit does not plunge at that point -it does that clear across the other side of the box!

[Rob Gunn]

Looks like a hesitation in your program that may be caused buy a communication hesitation between your computer and the Machine? I have seen other CNC machines do this. Can you physically see the ShopBot stop, jump, hesitate, jerk... ? Maybe slow the feed way down on a practice part and see if you can eyeball the issue. I may be off base but take a look and good luck.

[Brady Watson]

It looks like that is where the start/end point is.

Select the part in software and go into Node editing - Is there a node there? Does it need to be there?

-B

[dhunt]

Looks like a hesitation in your program that may be caused buy a communication hesitation
between your computer and the Machine?
I have seen other CNC machines do this.

Can you physically see the ShopBot stop, jump, hesitate, jerk... ? ===> No.
Maybe slow the feed way down on a practice part
and see if you can eyeball the issue. OK -thanks for the suggestions...

Cutting speed is presently 1.3 ins. per sec.
Couldn't hurt to slow that down to 1 in. per sec. or less..
but maybe too I should also FE the cut file and see if there's a built-in hesitation, for whatever reason.

A bit later...
OK I have now FE'd the cut file and identified the lines of code that cut this particular dimension.
I see nothing amiss
so I'm still thinking there's a physical bump or lump or gouge somewhere that's causing this.

[dlcw]

David,

I could also be the natural flex in the machine.

I know when I cut thick blocks, I first do a climb cut all the way around about 1/32" from my wanted cut line leaving a 1/16" skin. I then do a conventional cut on the wanted cut line and I don't have these marks.

[dhunt]

It looks like that is where the start/end point is.

Select the part in software and go into Node editing
- Is there a node there? Does it need to be there?The starting and end-point for the cut file is shown in the attached photo below
where you see the white pen at lower right.

The flaw is happening at upper left
-the dark pencil is pointing to the area where the flaw is occurring.



Nodes: Our Vector-9 software doesn't seem to have anything like Nodes anywhere in it.

I did as you suggested, selected the part (shows red in V-9)
and then had a good look thru all the possible options under File, Edit, Change, Draw, Axis, etc.
but no Nodes of any sort....not in Vector-9

[ken_rychlik]

You can ramp the down move in and that will help there, but it will still pull straight up when it's done cutting.

I have had to program a tail in some pieces and make the start point on the end of the tail.

There is also a lead in, lead out option on most of the vetric software.

I'm surprised you are able to hold those thick pieces in place with that large upcut bit pulling on em.

Wow, what is vector 9 ?

If your start point is where the white pen is, and you are ramping in, maybe that is the end of the ramp where it pulls up??

[dhunt]

I'm surprised you are able to hold those thick pieces in place with that large upcut bit pulling on em.

Wow, what is vector 9 ?Clamps may be primitive, but they work! ;)

God bless 'em --I've been clamping now for ten years.
Yes, we have a big old fancy suck-down thang behind the wall thar
we use it mainly when cutting fascia boards outa whole sheets of ply
but for smaller stuff, it's clamps and maybe a few judiciously placed hold-down screws.
Call it life in the islands?


_________________________________
What is Vector-9 you ask.

It's slow plodding Dutch software from ten years ago!
(-and IMServe doesn't respond to their emails! :mad: )

Ask the older guys on the Forum...guys who bought Bots 10-15 yrs. ago
when said Bots came with.......Vector-9!

PartWizard and PartWorks weren't even born then!:D

It's what we know, and it's very sure.
I have oodles of control over making toolpaths and cut files

[srwtlc]

David,

If you air cut this part, can you see any indication of a dwell at that point? If it pauses at all at that spot, you could get those marks from deflection in the gantry when it takes off again.

Try cutting at a different location on the table. Maybe you have a slight divot/nick in one of your rails.

VectorCam, not the fastest tool in the tool box, but if you learned how to use it well, there wasn't much you couldn't do with it. I still use it from time to time when I need a custom toolpath that can't be done with anything else. ;)

If you can't find a mechanical reason, I can take a look at the file for you Dave.

Scott

[meatbal80]

I had a similar problem due to my PC router. I found that the speed up ramp was to fast and did not alow for my PC Router to speed back up from in time.

[dhunt]

Try cutting at a different location on the table. ===> Further 'out' in Y...hmmmm...
Maybe you have a slight divot/nick in one of your rails.

If you can't find a mechanical reason, I can take a look at the file for you Dave.I had a fairly intensive look at the numerics of the cut-file myself.

Because the file has radiused corners, it's easy to ID the turning-the-corners lines of code
and therefore the straight bits too, between the corners.

I've identified the straight bits -per plunge- as it goes deeper and deeper over 6 passes, down to -1.80 inches
and there's no visible reason in the numbers, for this groove!


I've always suspected a physical,mechanical reason for this problem
and think your suggestion re. a nick in the Y rails is getting close! ;)

Will check that out tomorrow, definitely.


Given that the rails on this machine are "only" ten years old
and have suffered abuses at the hands of 'local' guys put to run the machine
i.e. total indifference to maintenance,adjustment,tightening,lubrication and other such 'bothers'
nothing surprises me or the boss, any more! :cool:

You should see what came out of the little grooves in the stainless wheels that run on the rails!! :eek:

[gene]

I cut some doors , 3/4 mdf and noticed that there were marks exactly like what is shown here , I used a 3" ramp and the marks were at the spot where the file ended . can you add a lead out without adding a lead in ? I am using aspire 2.5

[ken_rychlik]

Gene, The first thing I would do is tune up the machine and get rid of all mechanical slop that you can.

If you can't help it that way, you can create you own tails on the part to enter and exit with. The software will do lead in, but not lead out.

[dhunt]

- first thing I would do is tune up the machine and get rid of all mechanical slop that you can.
Mechanical slop is probably half the problem with this (Yr.2000!) PRT-96 I'm using
particularly after a Cuban guy has been using/misusing it for the last 3 yrs.
I say no more. Machine rehabilitation continues...

[tmerrill]

Ken,

Gene said he had Aspire 2.5 and it WILL do lead-outs, however it will only do a lead-out if you have set up a lead-in.

Same is true for V-Carve Pro/Partworks.

Tim

[bleeth]

Can you select the lead in toolpath and delete it?

If not you can modify the code by taking out those lines and substituting it with a plunge at the right point.

[ken_rychlik]

Tim,

Now I have to go back and look at those again. lol

[dhunt]

If you can't find a mechanical reason, I can take a look at the file for you Let's have a look at the latter section of the .sbp cut file
that liberates the box from the surrounding material.



After initial plunge to depth -0.3017 ......

CG,,3.5000,-0.2500,-0.6250,0.0000,,1 <=== turning the corner code
M3,0.3750,-0.2500,-0.3017 <=== short leg of the box
CG,,-0.2500,0.3750,0.0000,0.6250,,1 <=== turning the corner
M3,-0.2500,5.2500,-0.3017 <=== long leg of the box
CG,,0.3750,5.8750,0.6250,0.0000,,1 <=== turning the corner
M3,3.5000,5.8750,-0.3017 <=== short leg, across the top..
CG,,4.1250,5.2500,0.0000,-0.6250,,1 <=== turning the corner
M3,4.1250,0.3750,-0.3017
M3,4.1250,0.3750,-0.6033 <=== Second plunge depth begins here
CG,,3.5000,-0.2500,-0.6250,0.0000,,1
M3,0.3750,-0.2500,-0.6033
CG,,-0.2500,0.3750,0.0000,0.6250,,1
M3,-0.2500,5.2500,-0.6033
CG,,0.3750,5.8750,0.6250,0.0000,,1
M3,3.5000,5.8750,-0.6033
CG,,4.1250,5.2500,0.0000,-0.6250,,1
M3,4.1250,0.3750,-0.6033
M3,4.1250,0.3750,-0.9050 <=== Third plunge depth begins here
CG,,3.5000,-0.2500,-0.6250,0.0000,,1
M3,0.3750,-0.2500,-0.9050
CG,,-0.2500,0.3750,0.0000,0.6250,,1
M3,-0.2500,5.2500,-0.9050
CG,,0.3750,5.8750,0.6250,0.0000,,1
M3,3.5000,5.8750,-0.9050
CG,,4.1250,5.2500,0.0000,-0.6250,,1
M3,4.1250,0.3750,-0.9050
M3,4.1250,0.3750,-1.2067 <=== Fourth plunge
CG,,3.5000,-0.2500,-0.6250,0.0000,,1
M3,0.3750,-0.2500,-1.2067
CG,,-0.2500,0.3750,0.0000,0.6250,,1
M3,-0.2500,5.2500,-1.2067
CG,,0.3750,5.8750,0.6250,0.0000,,1
M3,3.5000,5.8750,-1.2067
CG,,4.1250,5.2500,0.0000,-0.6250,,1
M3,4.1250,0.3750,-1.2067
M3,4.1250,0.3750,-1.5083 <=== Fifth..
CG,,3.5000,-0.2500,-0.6250,0.0000,,1
M3,0.3750,-0.2500,-1.5083
CG,,-0.2500,0.3750,0.0000,0.6250,,1
M3,-0.2500,5.2500,-1.5083
CG,,0.3750,5.8750,0.6250,0.0000,,1
M3,3.5000,5.8750,-1.5083
CG,,4.1250,5.2500,0.0000,-0.6250,,1
M3,4.1250,0.3750,-1.5083
M3,4.1250,0.3750,-1.8100 <=== Sixth and final plunge
CG,,3.5000,-0.2500,-0.6250,0.0000,,1
M3,0.3750,-0.2500,-1.8100
CG,,-0.2500,0.3750,0.0000,0.6250,,1
M3,-0.2500,5.2500,-1.8100
CG,,0.3750,5.8750,0.6250,0.0000,,1
M3,3.5000,5.8750,-1.8100
CG,,4.1250,5.2500,0.0000,-0.6250,,1
M3,4.1250,0.3750,-1.8100
J3,4.1250,0.3750,1.6000
'MOVE TO X-Y HOME POSITION & THEN RAISE TO Z HOME
JH,
'DONE

...............................

Those lines of code in bold purple are the lines on which the groove is happening.

This is a simple rectangle being cut, with radiused corners.
Two long legs - in and out
Two short legs, one across the top ..the other at the bottom, near to me the operator

Looks like fairly straightforward numerics to me...
What do you think?

[ken_rychlik]

Have you tried reversing direction? climb/conventional ???

[Dusty Knobel]

I also use Vector ... (Vector 12 now!). I agree it is a good product. It can now process Rhino files even and has quite a few features. IMSRVE continued to support their product. Just support is limited , I believe , to latest version only. If you want to send me the file I can try it on my PRT. (furnituremaker atabout live.com).

Dusty
Olympia, WA

[Brady Watson]

I'll volunteer to toolpath in PartWorks, Aspire or ArtCAM Pro if you send me it as a DXF or EPS. This would eliminate it being Vector. Let me know the following:

1) Zzero on top of the material, yes?
2) Material thickness?
3) Stepdown
4) Speeds (you can modify via FE)
5) Bit diameter

Also, have you tried Scott's suggestion of cutting in a different location on the table?

-B

[srwtlc]

That snippet of code runs smoothly on mine and I see no indication of any hiccup in the code.

You haven't answered as to whether the machine actually pauses at that spot or if it's just a bump due to a mechanical issue and does it happen somewhere else on the table as well.

The only other thing I thought of was that way back when, there used to be an issue with loops from CG's and you needed to take values out to 6 digits past the decimal point instead of the default of 4, but the divot is happening well before the corner which leads me to believe that you may have a divot in a rail.

Check to be sure one of the workers/helpers doesn't have a rubber mallet in his back pocket and that he doesn't give it a whack at just the right time when you're not looking. In the picture, the divots are close to the same, but not exactly. He needs to work on his timing just a bit. ;)

[dhunt]

I'll volunteer to toolpath in PartWorks, Aspire or ArtCAM Pro if you send me it as a DXF or EPS.
This would eliminate it being Vector.

Let me know the following:

1) Zzero on top of the material, yes? ===> Yes.
2) Material thickness? ===> 1.75 ins. Mahogany.
3) Stepdown ===> 6 passes
4) Speeds (you can modify via FE) ===> 1.3 ins. per sec on the PRT-96
5) Bit diameter ===> Amana 0.5 ins. spiral upcut.

Also, have you tried Scott's suggestion
of cutting in a different location on the table? ===> Not yet.
Client difficulties in pressing on, at the moment.

-BIt's getting close to going home time, here
but a few quick answers to you helpful gents...

The client expects miracles without even confirming an order, or making a down payment. :cool:

We're not about to cut much more expensive mahogany, thus we're holding back a bit on this particular project
thus my not having made any further experimental cuts at difrnt parts of the table, etc.
but this will happen soon, after corrections to Z, which may well be part of the problem!

We have some Z issues with one of the two circular clamps that hold the Porter Cable to the Z column
-those should be addressed tom. a.m. since we have two new hose clamps and carpet tape
---just waiting on the boss to get back in town and we'll fix it up hopefully
...it takes 4 or 5 hands, needs squaring up too! :cool:

[dhunt]

That snippet of code runs smoothly on mine
and I see no indication of any hiccup in the code. ===> What I thought

You haven't answered as to whether the machine actually pauses at that spot ===> No it doesn't.
or if it's just a bump due to a mechanical issue ===> More and more, it's seeming so...
and does it happen somewhere else on the table as well. ===> I dropped the X and Y motors this morning
and rolled the gantries around a bit -they seemed OK
but for an abused machine of 10 yrs. old, it's kinda hard to judge?

Running a finger along the rails(which prob. need replacing?)
there are minor inconsistencies, but nothing glaring.

Problem could be a combination of dodgy rails and fluctuations in Z?

The only other thing I thought of was that way back when,
there used to be an issue with loops from CG's and you needed to take values
out to 6 digits past the decimal point instead of the default of 4,
but the divot is happening well before the corner
which leads me to believe that you may have a divot in a rail. ===> It's not the smoothest!

Check to be sure one of the workers/helpers doesn't have a rubber mallet in his back pocket
and that he doesn't give it a whack at just the right time
when you're not looking. ===> Life in da tropix, huh? You live here too? LOL

In the picture, the divots are close to the same, but not exactly.
He needs to work on his timing just a bit. ;) As stated in previous post, I haven't been too adventurous re. cutting elsewhere/experimentally
coz this is expensive Mahogany and the client is...well.....never mind...


and like I said, there ARE Z issues to be corrected and then we'll get experimental, I'm sure.

This problem has to be physical/mechanical....rails, fluctuations in Z or in Y(rails)....

[dhunt]

I also use Vector ... (Vector 12 now!).
I agree it is a good product. ===> So we're 'slightly behind' with V9 huh? LOL

It can now process Rhino files even and has quite a few features.
IMSRVE continued to support their product.
Just support is limited , I believe , to latest version only. ===> That may explain
why we haven't heard zip from them about getting our Vcarve (sp?)program working again.
Thanks IMServe.

If you want to send me the file I can try it on my PRT.
===> ..I just sent it
Almost certainly now, this prob. is mechanical? not in the Vector geometry or the N.code
(furnituremaker atabout live.com).

IMServe's service overall is not impressive.

If/when we change software, I doubt we'll go the IMServe/Vector route
which is a pity.

If they want me to change my mind, they might respond to last week's email? :cool:

[ken_rychlik]

Hose clamps to hold a router in place is kind of scary all by itself. They make real mounts for those things you know.:rolleyes:

[dhunt]

Hose clamps to hold a router in place is kind of scary all by itself.
They make real mounts for those things you know.:rolleyes:Hey, this is life on a small tropical island.

http://i177.photobucket.com/albums/w219/aplmac/Carnival%20VICTORY%20-%20Nov%2008/BARBADOS/Lobster-409.jpg
This is Carlisle Bay -about 5 mins. away from my house!


Wouldn't be fun if we weren't using lo-tech stuff like Bamboo an all.

We bin using two stainless-steel hose clamps to hold the Porter Cable in place now
for ten long years.

It works... most of the time....but tell me about those Real Mounts.

A URL would be nice..

[Brady Watson]

That mount is junk. It was OK for a PR back in the day that didn't go over 2 IPS and Z speeds 1 or under. The machine probably had enough slop in it to mask the flex in the mount. Get one of the cast AL ones:

http://www.shopbottools.com/files/SBDocs/SBG00319090824PRSAssemblyBinder.pdf

Page 35 - "Mounting the Router or Spindle"

You'll have to call SB for a price.

-B

[dhunt]

That mount is junk.

It was OK for a PR back in the day that didn't go over 2 IPS and Z speeds 1 or under.
The machine probably had enough slop in it to mask the flex in the mount. ===> Allegedly accurate to 0.015 in.

Get one of the cast AL ones:

http://www.shopbottools.com/files/SBDocs/SBG00319090824PRSAssemblyBinder.pdf

Page 35 - "Mounting the Router or Spindle"

You'll have to call SB for a price.

Thanks for that link.. Will try to act on that

If we run the old girl at anything over 1.5 ins. a sec. we are in a tearing hurry :D
so it has suited us just fine, so far
but yes I recognize the inadequacies of ten year old technology :cool:

[Brady Watson]

The 10 yr old technology has served me well...but I have upgraded to PRS Alpha drives and a PRT Alpha gantry. I welded my old PRT gantry to beef it up and that worked out well too.

If you maintain, tighten up & gusset these machines where they need it, they can perform like a new tool. Every little bit makes a difference.

-B

[dhunt]

The 10 yr old technology has served me well...
but I have upgraded to PRS Alpha drives and a PRT Alpha gantry.
I welded my old PRT gantry to beef it up and that worked out well too.

If you maintain, tighten up & gusset these machines where they need it,
they can perform like a new tool. Every little bit makes a difference.
I appreciate all of what you say.

Problem here is the 'local' guys who get to run the machine for a spell, between my spells here.
That's when things slide.

Locals simply don't do maintenance.
No grease on the rails for years, muck in the wheels,
this slack, that slack...
They simply don't care. Someone else will fix it. That Someone is Me.

Every now and then I get called to the breech
and we do big rehab's of the machine that make it last another few years.

Life in da tropix! :D

[Brady Watson]

There's a sayin' down there in them parts: "The beatings will continue, until morale improves!"

Maybe that should be changed to: "The beatings will continue, until maintenance improves!" :D

-B

[srwtlc]

Hey Dave,

You should go back to Paul's and ask him to let you play with his VCarve Pro software. That is if he's not out fishing in that new boat he built! :D

Better yet, download the trial version from Vectric's site.

Keep Vector handy for those special ocassions. ;)

Scott

[dhunt]

There's a sayin' down there in them parts: "The beatings will continue, until morale improves!"

Maybe that should be changed to: "The beatings will continue, until maintenance improves!" :D ===> Hell yes! Hey, it's either we cry or we laugh, eh? - Better we laugh...

As indicated previously, life is very different in these parts. ;)

_____________________________________

Attached is a picture of our latest technological improvement and possible cure? to the groove problem
although we're busy cutting a gingerbread pattern fascia board order right now
so the groove problem(or its cure) will probably not show up..

Three hose clamps securing the Porter Cable -how hi-tech is that, huh? :D

Actually they're doing a pretty good job,
but we are considering that cast aluminum mount to do a better job.

[dhunt]

You should go back to Paul's and ask him to let you play with his VCarve Pro software.
That is if he's not out fishing in that new boat he built! :D

Better yet, download the trial version from Vectric's site. ===> Have done so, but so strangely difrnt from Vector!

Keep Vector handy for those special occasions. ;) That is a nice boat he built. I saw it in his shop and was admiring it.
It's got nice lines....

_____________________________

Yes, sooner or later we have to move up from Vector
and a few instructive VCarve Pro lessons from Paul will become necessary.
I can see it in the future. ;)

[jerry_stanek]

I ran the code on my PRS standard and it cut just fine