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load
06-16-2004, 11:53 PM
o im useing PW to as my acad and use 2.38 dos SB for my cutting program. whart im getting out of my parts is when i do stight cuts the tool gose in a stright line to where it maks an angle then when it getthrou the angle im makes nipple and gets back on track to where it should be cutting.

how would i fix that? change my ramp speed, slow the machine down, do i need to make a soft angle in my part *a curve vrs a 90 degree angle?
thank you for your time
Paul

Brady Watson
06-17-2004, 01:09 PM
Paul,
It sounds to me like you are using the 'Machine Along Vector' toolpath option...that's why you are getting that little nub at the end of each toolpath. Be sure to make lines to machine shorter in length by 1/2 of your bit diameter to avoid this.

If you want to make a curved corner there are a couple of ways to do it. 1st you should join and close the design (lets say a 45/45/90 degree triangle...even if you only need 2 legs of it to machine) After creating this, you can offset it the diameter of your bit, and then run an INSIDE profile cut on it to get the curved corners. An outside profile would give you square edges. You can also transform the offset that has the filets on it to your orginal size and do it that way.

You can also edit out the legs that you don't need and machine along vector. Offsetting a squared corner will give you a fileted corner when offset. You can also manually add filets to your corners using the arc tool. You will have to add and remove points in PW to get a nice joined shape.

Hope this helps...there's always more than one way to get the job done...SO you might find another way than my suggestion.

-Brady


4196

load
06-17-2004, 10:58 PM
actualy i forgot to mention that im useing an outside profile cut. what im doing are the letters of the alphabit and when ever i have an inside cut like on the letter R where the machine is cutting the inside of the R and along the stright part and dose the 90 degree angle to start the arch it leaves the nipple also lets take the letter H, the lines are all stight but when it is cutting on the inside of the legs i get a nipple, they both are done by closed vectors and the profiles is an outside profile cut, im useing a 1/4 inch bit one 1/2 laminated mdf and its a cut through how ever do do have it set up to do a single pass cut at the feed rate of 1.25 inchs. Could that be my problem right there is trying to cut to much in a single pass? i have not tryed to set the file up to do a multi pass yet becouse i was hoping that i could find the solotion from a past experence befor i go in and tinker around with my files to much.

thank you again
Paul

Brady Watson
06-17-2004, 11:36 PM
Yes Paul...I would say that you are A) Moving too quickly through the material and B) taking too much off in one pass.

You did not mention how tall the letters were. It is *possible* that you are losing steps when the machine makes the turn at that speed and also possible that the force of going through 1/2" material in one pass is making matters worse.

Just for the heck of it, change your move speed to .5 or .7 and .2 on the Z. Also change your bit stepdown to .375 so that it will make 2 passes through the material. All of this is very easily done in Part Wizard. When you make your toolpath, and select your bit, hit the dropdown under where the 'select' button is for the bit. Change the stepdown and speeds there or change them in the tool database itself.

I think this will solve your problem. Give it a try on ONE letter in a scrap piece...not the whole file to save on material.

Let us know how you do.

-Brady

load
06-20-2004, 12:15 AM
i played with part wizard enought and that is how i learned as far setting speed and the step down rate which was the reason i asked if that could be the issue as far as the missing points not the issue cuz when it make a stight cut it is set to go from one point to the next nothing between it as an exsample m3 2.000,2.0000.510 m3 6.0000, 2.0000, .510 then m3 6.000, 5.000, .510 that is an exsampl to how the program is layed out and i would get that nip right after it make the 90 degree angle to the next point but im going to try changeing the stepdown rate and the move speed from there.

thank for the input
paul

greg_russell
05-11-2005, 08:32 AM
I am having a similar problem and so I thought I might resurrect this post. I use PW to design and generate my cut files. I am using the profile on the outside tool path. When cutting ¾ (and 5/8) Baltic birch, in two passes with a ¼ bit, I am getting a little “bump” in the cut. The bump occurs when the initial plunge is made into the material, and again in the same place when it plunges for the second pass. It seems like the tool is plunging outside the tool path, and then moving back to the tool path. I generally cut about 2.2 IPS, with a .375 step down. I have slowed down my feed rate as far as 1.5 IPS and still get this bump. So it does not appear to be speed related.

I have the most current windows control software loaded, I have check all my hold down rollers, pinion gears, grounding, etc. I can not seem to fix the problem. So I have come to the conclusion that it is software related. Is there a setting that is causing the tool to plunge outside the tool path? BTW I am using the original PW version I got with my tool (1.02).

Thanks for any help and or suggestions you might have.

Thanks, Greg

fleinbach
05-11-2005, 08:44 AM
Paul and Greg,

This issue is not software related. The nip you are getting when entering the material is caused by the bit pulling itself into the material. This comes from the free play in the Y carriage usually. The first thing I would check is to make sure your V bearings are adjusted as snug as you can get them. Even when they are as tight as they can be you will still get the nip. The best way to compensate is to use the cleaning path method. This not only removes the war line marks but will also clean up the corners were the bit first starts a new direction.

I would go into more detail but I have to leave for the rest of the day. More than likely one of the other guys may jump in and explain in more detail using the cleaning path. Brady actually described it just recently in another post.

pete
05-11-2005, 09:20 AM
Greg, isn't the plunge outside the toolpath a selection you make, called a lead in - when you are generating your toolpath in PW? I don't have PW at this location so that I can get all the words right, but I think you have two choices at the bottom of the toolpath set-up window, one is lead-in and the other is bridge. Pete

greg_russell
05-11-2005, 09:41 AM
Frank,

Thanks, I will go back and check my v-bearings again and see if that helps.


Pete,

In the version I am using that is not an option. It may well be in the newer version.


Greg

guest (Unregistered Guest)
05-12-2005, 08:05 AM
I just changed to version 3.4.1 of the new controller software and get the same problem as the rest of you. I do believe that it is entirely software related since this ONLY started after installing the new controller software!

This makes it hell on creating parts that don't have extra material on them.

BTW. I have also checked all of my pinion gears for tightness. As a matter of fact, I took my machine down to the table to see what was going on. Took off the z car, the y car and the x car. Then I took of the x rails to make sure it wasn't the machine.

This extra nub also happens when using software other than PW.

This many people having the same problem doesn't sound like a setup problem to me.

fleinbach
05-12-2005, 09:06 AM
guest

Can you send me the DXF or DWG file you are trying to cut? I would like to run it for myself to see what you are talking about. Maybe I am misunderstanding what you are saying.

gerald_d
05-12-2005, 09:25 AM
What happens when you cut in the opposite direction around the profile? This will help to tell whether deflection and stuff are involved. This discussion (http://www.talkshopbot.com/forum/cgi-bin/discus/show.cgi?tpc=315&post=18405#POST18405) may also be relevant.