Bobcad!!! What great software. Just wish I knew how to use it better!!

I've been trying to draw a simple dome shaped object but can't seem to get things to smooth out. I've tried to merge part of a sphere and a small cylinder but have not been successful. The following are the design criteria.

Round object 3.1" OD. I want the bottom to be a 1/8" cylinder with a dome on top of that which will yield a total thickness of 3/8" at the highest peak. I'm going to machine this out of a 3/8 or 1/2 inch flat stock aluminum. It's going to be a new engraved point cover for my Harley.

Any help will be appreciated. Hope I've listed enough info.

Happy Holidays.
Bill
:)

Bump - Happy Holidays.

can you send me what you have so far so i can understand? i maybe able to help

Bill,

Please post a sketch or a CAD File for everyone to look at. I'm confused as to what you want to do. Maybe a Tapered Cone with Radial Ends or two Arcs with Tangent Lines.:confused:

This was done using a portion of an elipse with a short line attached to one side. I used revolve surface to make the surface. Hope it comes through.

Thanks Guys.
Not enough info, that's what I was afraid of. This is a simple disk with a base of 1/8 inch. The top of the disk will be dome which is .375" from the bottom at the highest point (dome section will be .25"). I'll attach a simple dwg which is a side view sketched in bobcad with the rectangle function and the arc through 3 entities function. Hope this clarifies my request a little. I know it's simple to do (most likely) but I can't seem to find the right combination. My goal is to take this drawing and project different images/engraving on it to give it a custom look to show off to all my harley buddies. I'm going to tell them I did it all by hadn which is true. I just used a cnc machine as a tool!!!
Sketch attached and thanks again.
Bill from Spartanburg

hi. is this the right idea not sure about the edge thickness? select it all then render it. look on the solids menu if you arent familiar with render

Thanks for the dwg. The cover I'm invisioning does not have a lip as shown on your drawing. It's basically a flat disk 3.2" in diameter with a domed top approximately 3/8" thick at the top of the dome. If I could figure how to take a 3.2" piece of round stock, placed vertical in the vise, cut a dome on the top of the cylinder (this is where I'm struggling), then part of the dome to make the disk. Sounds simple doesn't it???
Thanks again.
Bill from Spartanburg.
:rainfro:
(love the fro)

is it creating the g code from the drawing thats difficult? what version of bobcad do you have? for this item you would probably want a spiral or radial toolpath. let say you have the exact item you want to machine on the screen in 3d, are you able to create a toolpath? Do you know how to turn the toolpath into g-code? At which point do things get trickey for you :) im sending a radial toolpath of a shape similar to what you describe. when they open you need to turn on 3d view or rotate them manually otherwie you cant see the dome aspect of it since the view defaults to straight above.

Bill this is not Bobcad but is this what you are looking for? Rhino in just a few seconds.

Mike

ps projecting on the surface in Rhino is quite easy as well. If you need anything else let me know.

Bill
I have a program that is still in development but should do what you want.
If you wish to try, use the Arc-Convex Option and enter your radius figures as positive numbers. You will also need to enter a radius figure.
I've entered some figures to help. Pic attached to help explain.

Mike;
Your spot on!!! This is what I'm having difficulty trying to generate in Bobcad. Seems simple but I can't do it for some reason. Wish I had a copy of Rhino to play with. Thanks.
Kiwi,
Nice program. A little later (I'm moving my brother today), I'll play with it and get back to you. I know it will work for me. Your example is very impressive.
E42,
Thanks for all the help. I'm not haveing the troubles you mentioned just can't draw the part in 3D as mike did above. Simple but why can't Bobcad do it. Sorin, where are you when your needed??? (Most probably working and on the road).
Thanks again Guys.
Have a happy new year and be safe.
Bill from Spratnaurg.

here you go. in bobcad so you can work with it. this is exactly the shape you specify. 3.2 across .125 cylinder and domed to .375 or 3/8 at the top.
im still not seeing what the actual catch is. is just getting this shape drawn on screen the problem or is the converting it to g code the actual problem.

Bill you can download Rhino demo for free and can even save several times.

I'm curious what version of Bobcad you're using. The model I posted for you was done by taking your dxf, rotating the geometry 90 degrees, picking the center of you bottom line and doing a revolve of 360 degrees around that point. Saved, screen shot and posted. If you are using one of the later versions of Bobcad, I'll nearly bet you it has some sort of revolve command somewhere. Now on the other hand.......I have been wrong before!:) My latest version of Bobcad is 17 and I do still use it some, but the more I use Rhino and Madcam the less I use Bobcad. You might also want to go to the Rhino forum and check out the offer by Madcam......:banana: FREE software!......:banana:

Mike

You are correct Mike, there is a rotate in v20-21 at least, if it was there on 19 its not as easy as it is now at least. the way you present it seems as tho you are recommending a change from bobcad. I feel that people should be helped to work with what they have,(not that you didnt) most of us are hobbiests and would better spend money elsewhere. every software has its advantages as well as faults. In the long run its probably better the long run to learn how to do some of the fancier things without some of the fancy features that are out there. It expands problem solving skills. I know in my shop that im always having to adjust my way of doing something so as to stay within the limits of my tools and software. Anyway im not throwing stones or anything, but i dont want to Bill to feel like he has something inferior just because of some difficulty with one aspect. ok im done :) no harm meant.
{oh i expect Bill to cnc "Made with BOBCAD" onto that part when hes done too LOL :) }

Ed

You are correct Mike, there is a rotate in v20-21 at least, if it was there on 19 its not as easy as it is now at least. the way you present it seems as tho you are recommending a change from bobcad. I feel that people should be helped to work with what they have,(not that you didnt) most of us are hobbiests and would better spend money elsewhere. every software has its advantages as well as faults. In the long run its probably better the long run to learn how to do some of the fancier things without some of the fancy features that are out there. It expands problem solving skills. I know in my shop that im always having to adjust my way of doing something so as to stay within the limits of my tools and software. Anyway im not throwing stones or anything, but i dont want to Bill to feel like he has something inferior just because of some difficulty with one aspect. ok im done :) no harm meant.
{oh i expect Bill to cnc "Made with BOBCAD" onto that part when hes done too LOL :) }


Ed


He better have version 21 then. Look at the engraving on 3d in bobcadcam post.

You are correct Mike, there is a rotate in v20-21 at least, if it was there on 19 its not as easy as it is now at least. the way you present it seems as tho you are recommending a change from bobcad. I feel that people should be helped to work with what they have,(not that you didnt) most of us are hobbiests and would better spend money elsewhere. every software has its advantages as well as faults. In the long run its probably better the long run to learn how to do some of the fancier things without some of the fancy features that are out there. It expands problem solving skills. I know in my shop that im always having to adjust my way of doing something so as to stay within the limits of my tools and software. Anyway im not throwing stones or anything, but i dont want to Bill to feel like he has something inferior just because of some difficulty with one aspect. ok im done :) no harm meant.
{oh i expect Bill to cnc "Made with BOBCAD" onto that part when hes done too LOL :) }


Ed

Ed no harm felt. I was a 14 yr user of Bobcad and purchased all upgrades during that time up to 17. While I have suggested he download Rhino (free) and Madcam (free) it was merely a suggestion to see what might help him. I have never bad mouthed Bobcad and have tried to help where I could. Sorin is a friend of mine and and personally think he is the greatest asset Bobcad has going. That did not make me upgrade the last four times though!:)

I did consider not posting the Rhino info because I have a real distaste for using one forum to promote another. In this case I was just trying to help.

Mike

sorry, i guess my shorts are a little tight today or something , but its all good, ill send a beer your way. Bill has been quiet today, I hope he's machining that part :)

Ed I was not offended, but I did feel the need to explain myself. Thanks for the offer of the beer, but I'm non drinker. On the other hand if you want to send a few pounds of t bones on dry ice...................:D :D :D

Have a good one. We're getting the rains that was snow in Denver....possible flooding tonight.

Mike

flooding? you need to move to florida where the weather is much more stable. we havent been hit by 4 hurricanes in a 30 day period for over a year now!
Bill let us know how you made out. To keep this on topic, Bill try playing with the primative solids and boolean functions in bobcad. you could have easily made your shape using that method as well. its more of a sculpting effect, make a sphere with the right radius on it, trim the bottom off and trim the sides down. i wish i knew what version you had, the use of booleans is nicely illustrated in v 20+

Hey Guys;
Thanks for all the input. E42, I was having touble drawing the part. I tried using the primitives but could not quite get the part to look right. I'm a new user so forgive me the struggle. I'm also a dedicated user of Bobcad since I decided on it and purchased it. I have the latest version and can't wait for the new one (if I can afford it)!
I asked about Rhino just because I'm curious about other ways of doing things. BTW, I have never seen the revolve command used so I didn't know of its existance. Guess I was asleep during that part of the training CD. I'll load it and review it again. Those videos are great but a lot to learn.
Thanks again guys! I'm going to try and finish a power drawbar today for the lathemaster then on to cutting domes for this domeless person!!!
Happy New Years.
Bill from Spartanburg.
:) :)

Bill what version of Blbcad do you have? Come of fess up. Have they got you testing v22 for them? If that package does all they say it will it is going to be a good one.

Ed, I know about the weather you have there. My son in law does storm cleanup and has been to Florida several times for that.

Mike

Hey Mike;
I'm using version 21.5.2 and unfortunately, will only test ver 22 after I pay for it. Oh well, still love the software. I'm a hobby user and do not have machinist experience but I do love it so!!! hooked as they say.
Have a great day all!!!!
Be safe.
Bill :cheers:

HI Bill. with the revolve command under the solids menu, you can very easily visualize any thing you could possible cut on a lathe. something like this can be drawn in a few seconds. have fun with it, its free :)

Bill
I have V20.7 and this is how I have done the dome.
I'm open to better/faster ways to get the part drawn with BCC.
Draw three lines
X-1.6 Y0 to X1.6 Y0
X-1.6 Y0 to X-1.6 Y0.125
X1.6 Y0 to X1.6 Y0.125
Point, End of each line (upper end)
Arc through 3 Entities (the three points)
Change,Trim (all lines left of the centre line)
All Change Rotate (3D) X90
Pick 3 profile lines (not centre line - arrows must follow)
Solids/Surface/Revolve/360deg Pick Linea/OK/Pick Centre Line

bill could you post your g-code for just the dome. I am doing some of the same parts right now. I have the design and the file is all stepped but now i need to dome it like you were showing. Any advice on a walk through of how to do this would be great. I am using the updated ver21 of bobcad

Hey Krimis;
I generated this code but have not tried it yet. I looks OK on the screen but you know how that is. Maybe someone with experience can look at it and give us some pointers. Anyway, enjoy and have a good day.
Bill
:D

Bill S
Ran your code with BCC simulator with ball nose cutters 0.25" and 0.5" and this is the result. Not sure what dia. cutter you had planned to use but this will alter the outside diameter.
I also see some blank lines N7284 and N7292. My controller would stop at these points.

Thanks Kiwi;
Again, I had not tried the code and this is most definately not the smooth surface I'm looking for. Guess I'd better start adding motors to my lathe!!!!
Thanks again.
Bill
:o

Bill did you actually carve one of the domes? Many times the resolution on the simulators are not as good as the part itself. What kind of stepover did you use for the toolpath? What bit did you use? Now I don't think you will ever get a part like this as smooth on a mill as you can on a lathe, but you can get it better than the simulator photo shows.

Mike

Bill S
I see the tool does all the passes at the same step-over.
Suggest you do a finishing pass at a smaller step-over.

it would seem to me that you could get a better finish on this shaped part with a radial toolpath? doesnt the domed shape lend itself to that.

erase42
With a radial toolpath the cusp height will get greater towards the edge along the radial line.
With a spiral toolpath the cusp will be more consistant with a variation from the near flat in the centre to higher as the side gets steeper.
I think the spiral with a small stepover will give the better finish.

I typically do solids with sepperate paths for roughing and finishing.

Rough the entire form with a larger stepover and leave stock in solids by cheating a little.

I transform my part up in Z (.01"-.02") before posting the roughing cuts so it will not finish the depth. Also lie about the tool diameter to leave stock on the walls when generating.

Translate the part back to the finished Z position then generate the finish cut.


BTW: Did you know you can limit the inside by using double boundries?