×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Lofting (I suppose)

Lofting (I suppose)

Lofting (I suppose)

(OP)
Here is my situation.  I have a cylindrical can and I wish to mill an 1/8" deep slot all the way around it.  This slot however needs to be tapered such that the tool itself will move downward ('z' direction) as it is rotated around.  This will give the appearance that it is spiraling downward as you rotate the can.  I am trying to us a loft, however, I am having trouble establishing guidlines that will curve with the outside of the can while moving downward as well.  I have some pictures that I can e-mail if that would clarify.  Thanks for your help in advance.

Brian

RE: Lofting (I suppose)

Sounds like you need to use a Insert > Cut > Sweep

Check out:-
Thread559-41468
Thread559-58350
and for an alternative multi-body method Thread559-44827

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

The centerline of the slot bottom is a spiral.
Insert --> Curve --> Helix/Spiral

Try making your slot constant depth.  Extrude a surface that represents the spiral bottom, then replace the bottom face of the slot with the spiral face.

Due to illness, the part of The Tick will be played by... The Tick.
http://www.EsoxRepublic.com

RE: Lofting (I suppose)

Deep sigh .... I really have to start reading these posts, at least twice, before I jump in with both feet ..... in my mouth.

Quote (MarkTwain):

"It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt."

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

Tick, I don't think that gets him where he wants to be does it?  He had a tapered tool going progressively deeper - thus the slot would get wider at the top.  Wouldn't your method have a constant top width but varying depth and bottom width?

John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics

There are only 10 types of people in the world - those who understand binary and those who don't.

RE: Lofting (I suppose)

He doesn't mention having a tapered tool.

RE: Lofting (I suppose)


Creigbm
Methinks you need to explain your problem again. We appear to have several different interpretations.
Are you trying to make your spiral slot:-
1) constant width - increasing depth
2) constant depth - increasing width
3) increasing depth - increasing width

Also is you cut profile rectangular?

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
Ok, lets try this again  :)

I am trying to mill a slot in a can that will move down the can as you turn it.  It is almost like a helical cut, with a constant width and depth.  I tried creating this using a loft but I am having difficulty with creating the guidelines (If you are wondering why I am using a loft, I cannot find a way to create a revolved cut that will 'spiral' down the can so I am using a loft to add material rather than take it away.  This is a backwards way of doing it and not the most efficient.) Think of it this way.  Take your pencil and spin it between your fingers.  Now with your other hand, put one finger perpendicualar to the side of the pencil and move it down towards the eraser.  I am trying to create the cut that your finger would make if it was cutting into the pencil.  Hope that helps to better define the problem.  Thanks for all your input so far.

Brian

RE: Lofting (I suppose)

In that case my first post would be correct!

However, in your original post you said "This slot however needs to be tapered such that the tool itself will move downward ('z' direction) as it is rotated around

So I'm still confused

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
The slot itself is not tapered (wrong terminology).  I will have to tryout the cut sweep (I have been only using lofting).

RE: Lofting (I suppose)

Try a sweep with a path and a guide curve. Make a helix for the path on the surface.  Make a second helix of same length and turns but larger diameter for a guide, to orient the "cutter path".

RE: Lofting (I suppose)

(OP)
I just tried creating a sweep using a helix for the path.  It works, however (and this is where I am getting picky), if you zoom in really really close you can see that there is a double edge where it seems like the sweep is not following its path 100%.  This is what I did if you would like to see what is happening.  I created a sketch of a square that would serve as the milled slot.  Then I created a helix a number of different ways (corner to corner, center to center).  They all worked in the sense that the cut was created.  Then I turned in the centerline and zoomed in really really close to notice there is a sbouel line (in wireframe) or a slanted edge if you are in shaded mode.  I was reading up on lofting and sweeping in 2004 and they claim to have updated it but it is not fixing this problem.  If there is a better way to do this, please let me know.
 

RE: Lofting (I suppose)

Send the file to the address listed in my profile. I will take a look.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
SBaugh,

I tried adding four guidelines to create the loft feature (one at each corner) with no luck.  I even added an extra profile midway through the loft/sweep and noticed that even though the guideline went straight through the corner of the profile, the loft itself did not represent that. There was still the appearance of a double line.

RE: Lofting (I suppose)

What SW version are you running and SP?

From one of your posts it sounds like your using SW03. If that's true. Then I think your seeing and bug in SW03. I thought they fixed it in a later SP of 03 but I'm not certain anymore.

Let me know... You can send me the file if you want to. My email is located at my website.

Regards,

Scott Baugh, CSWP
http://www.3dvisiontech.com
http://www.scottjbaugh.com

FAQ731-376

RE: Lofting (I suppose)

(OP)
I am using SW04 SP3.0.  I just e-mailed you the file Scott.  Thanks for your help.

RE: Lofting (I suppose)

I'd like a whack at this. Email address in profile

RE: Lofting (I suppose)

Creigbm:

I took a stab at this without seeing your model.

<http://www.esoxrepublic.com/models/>
SpiralCut.zip

There are two models: one with section normal to helix and one with section plane through cylinder axis.

Due to illness, the part of The Tick will be played by... The Tick.
http://www.EsoxRepublic.com

RE: Lofting (I suppose)

(OP)
Roland,

Thats the same thing I did (on SpiralCut2).  See here is my problem.  Turn on 'Axis 1' and zoom in really close.  There is still a double line from the sweep.  If anyone was wondering why I am worrying about this is we are working with our shop to get them import the SW model to mastercam.  I forsee double lines laeding to a lot of trouble in the future.

Thanks,
Brian

RE: Lofting (I suppose)

Please clarify "double lines".  Do you mean the appearance that the groove edge does not appear normal to the sylinder surface?

RE: Lofting (I suppose)

Same here ... no double edge anywhere.

Have you been to the optician lately ... just kidding.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

I cut sections through the cylinder axis to examine the groove.  The groove walls are perpendicular to the axis and to the cylinder face.

RE: Lofting (I suppose)

Ja.

RE: Lofting (I suppose)

Still, doesn't hurt to double-check.

Creigbm, you aren't depending on the screen output to make this determination, are you?

RE: Lofting (I suppose)

creigbm,

If I understand you correctly, you are making what I call a barrel cam.  The only way I have had success makeing these in Solidworks is to make a cylinderical surface, draw your path on the surface and create an offset the width of the follower.  Trim the surface into two pieces with the path and its offset. Then thicken the cylindrical surfaces the depth of the slot.  Surfaces always thicken perpendicular to the surface. This will give you the perpendicular walls you want with a constant width from the offset trim.  I hope I made myself clear, if not let me know here in the forum and I will email you an example.

Timelord

RE: Lofting (I suppose)


TheTick
I'm thinking the same as you, It seems like it's the screen resolution that's at fault here.

Creigbm
Can you measure between the "double lines. Also can you capture a screen shot & send the jpg or bmp file to us.

timelord
That seems like an unecessarily complicated way of creating a relatively simple feature. I know surface thickening definitely has it's place, but I don't think it's here.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
I am not completely relying on the screen output since a circle is never completely a circle.  This is how I did my verification.  I took a section cut through the part and measured the distance between one of the edges of the cut and the top of the can.  If the cut was correct, then these two edges would be parallel and would state so when I measured this distance.  Is there a way to post a picture in this forum?

RE: Lofting (I suppose)

Images
Use the [img] tag to show images from any web server. Be sure to use the entire url to the image you want to use including the "http://"


(no line breaks)

This can be found under Process TGML which is under Step 2 Options of posting a thread.

Regards

Scott Baugh, CSWP
http://www.3dvisiontech.com
http://www.scottjbaugh.com

FAQ731-376

RE: Lofting (I suppose)

creigbm
You need to be able to place the file onto a web server & then reference it here using
{img http://www.yoursite.com/filename.gif}
NOTE you will have to substitute the {} for []

if you don't have access to a web server then email as before & perhaps one of us can publish it.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
Thanks for all of your help.  I think at this point I am going to put this to rest and use it as is.  Is is close enough and I am just nit picking since I feel that if you are going to model something, you might as well do it right the first time.  The distance between the lines is 0.00000000 but it does not state they are parallel.  I spoke with the guys here using mastercam and they said that the double line I keep speaking of will not affect their process since you have to zoom in really close.  Thanks again.

RE: Lofting (I suppose)

(OP)
I think I have discovered what the problem is.  Can someone publish a picture on a server if I send it to them?  This picture will prove what I am trying to do and you will visually see what I am running into (all this after there haev been over 30 replies!!)

RE: Lofting (I suppose)

I got space.

RE: Lofting (I suppose)

Creigbm's file posted on my website in the models archive.  I'll leave it there for a month or so.  Zip file includes SW2004 part and JPEG screenshot.

<http://www.esoxrepublic.com/models/>
Creigbm--02Apr2004.zip

RE: Lofting (I suppose)


The Tick
Could not open the zip file. Tried from several different machines & several downloads, but kept geting "corrupt file" message. Anyone else have the same problem?

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

Grrr...

This has been a problem.  I contacted my web host (Yahoo).  They insist it's a problem with the downloader's web server.

Some people have no trouble at all.  I just tried it at home; no problem.  My work computer has trouble sometimes.  That is why most of my download points list actual bit count.

There are some programs out there that can help from the downloader's end.
<http://www.getright.com/>
<http://www.internetdownloadmanager.com/>
<http://www.bpftp.com/> Bulletproof FTP (I have this one)
<http://www.netants.com/> free
<http://www.freshdevices.com/> free

Due to illness, the part of The Tick will be played by... The Tick.
http://www.EsoxRepublic.com

RE: Lofting (I suppose)


TheTick
OK, ignore that last post ... FYI, if I "open" the file direct from your site it works fine ... but I cannot do a "save" from it.

Creigbm
After seeing the files I am now more confused than ever (admittedly an easy task) but ... what are we supposed to see???



Other than the profile not being drawn on a plane perpendicular to the helix (which would be correct if a round cutting tool was used) & an undercut being shown in the jpg (but not in the part), I cannot see what is wrong.

So ... apart from working brain cells ... what am I missing?

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
The problem with this picture is the profile of the helical cut is the same as the revolved cut.  I figured since both profiles are the same, I wouldn't get two different cuts as shown in the picture above.  I was hoping that the two surfaces would mesh into one (like it should).  I sent TheTick the model to so maybe he could post it on his website and look at that one to see exactly what is going on.  All I want to do is make a revolved cut and a helical cut mesh together.

RE: Lofting (I suppose)

OK ... finally I see what your concern is. The depth of the Extruded cut is the same as the depth of the Cut Sweep ... so there should not a visible line where the two surfaces join.

As your machinist correctly pointed out, the difference is so small as to make no difference in the real world, but if you were needing to do further work with surfaces in SW, this could cause problems.

I have tried various methods to eliminate the mismatch but without success & unfortunately I can offer no explanation.

Anyone else have any ideas? If not I would submit this to your VAR or SolidWorks to see if they can offer a solution or reason or identify it as a glitch.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
Now we are speaking the same language!!!  I am about to submit this to our VAR to see if there is a glitch and how to resolve this.  Any ideas are welcome!

RE: Lofting (I suppose)

You might be able to use Replace face or delete face to replace the split faces with a common surface.

RE: Lofting (I suppose)

You got it TheTick ... Delete face (the helical base) worked like a charm.

Creigbm
You should still submit problem to VAR & SW.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

Oops ... that should have been Delete face & Patch

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

RE: Lofting (I suppose)

(OP)
Indeed it did, nice work.  I just submitted it to our VAR to see what exactly is going on here.  Thank you all for your help, TheTick gets a Kudos for the day!

RE: Lofting (I suppose)

(OP)
FYI:  I spoke to our VAR yesterday and said that what I was trying to do was not possible because when SW creates a loft/sweep, it uses approximations which restricts it from creating a true curve.  I was looking in the 2004 whats new in SW book and it claims to have improved the loft command so perhaps it will get better in '05.  Thanks again for all your help.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources