First attempt at CAD and a engine design

[Metal Mickey]

Well in for a pound as they say.....after building the two wobbler's I started to think about an engine on the same principles but with two cylinders so it would self start (one hopes......(posh now I am using a computer)). I also am learning how to use BobCad Cad program.

So to recap, I am a novice engineer, a novice Cad user and a novice designer. Should be an interesting ride!

Anyway copyright accepted as the design will be worth a fortune...so its free if it works and for sale if it doesn't...Have I got that right? Anyway a few images to show where I am. Advice and constructive criticism welcome.

and where I am at the moment............

 

[malcolmt]

Hi Mickey
You are a brave man, your skills on the BobCad look amazing to me, I am just starting off learning turbocad and its daunting. If i may offer what little advice i can it would be that in order to self start the crankpins need to be 270/90 degrees apart.
I am really looking forwards to following this one through with you. Good luck.

Kind regards

Malcolm

 

[Brian Rupnow]

Mickey--Lookin good. Welcome to the wonderfull (and frustrating) world of 3D CAD. Malcom is correct about the offset of the crank pins for a self starter.---Brian

 

[Brian Rupnow]

Mickey--A bit of information, if you didn't already know. The cylinders must be double acting in order for the engine to self start.--That is to say, they must not only receive steam on the stroke where the piston is moving away from the "dead end" of the cylinder, but must also receive steam (or air) on the return stroke.---Brian

 

[BrianS]

Nice start with CAD. I have never used BobCAD but I've used AutoCAD for many years. If I may make a suggestion, you might want to make use of colors and make each part a different color. Also try to get in the habit of using different layers as well. They are a great help when the drawing starts getting complex.

 

[Brian Rupnow]

It kind of looks as if he might have modelled the entire thing as one part----

 

[Metal Mickey]

Hi Mickey

If i may offer what little advice i can it would be that in order to self start the crankpins need to be 270/90 degrees apart.

I am really looking forwards to following this one through with you. Good luck.

Kind regards

Malcolm

See, you just prove the value of the forum. Thanks Malcolm and noted.

Mickey--A bit of information, if you didn't already know. The cylinders must be double acting in order for the engine to self start.--That is to say, they must not only receive steam on the stroke where the piston is moving away from the "dead end" of the cylinder, but must also receive steam (or air) on the return stroke.---Brian

Well that's a second point of vital information. This may need some thinking about.........It may not be a self starter in version 1 which would lead to development potential eh! (Another way of say bit off more than.....)

If I may make a suggestion, you might want to make use of colors and make each part a different color. Also try to get in the habit of using different layers as well. They are a great help when the drawing starts getting complex.

Thanks Brian. Another important and usefull lesson which I will put right..........I did however build the parts i.e. cylinders, pistons etc. on different layers. Don't ask me why I did but through good fortune now it seems I fluked that one! So its not modeled in one go. I don't think my brain could handle it in one piece!

I will now go back and look at the work again. I may decide its best to get 'something' from drawing board to running (a major achievement if I did) and leave self starting and feeding air both above and below the piston, till version 2 (or 3).

One thing you may assist me with is how to convert the 3D to line drawings? I have good training video's but there is just so much to learn! A hint would help....... but I have more to do before I need to do that.

Many thanks gents for good advice.

Metal Mickey....

 

[Brian Rupnow]

Mick, in the software which I use, (Solidworks), there is no need to use layers. Layers is, I believe, more of a 2D Autocad thing. In my software, I drag and drop the solid model onto a pre formatted "Drawing sheet" and it automatically creates what views I ask it for. I'm not sure how you would do it. Does the program have a "Help" file associated with it?---Brian

 

[Metal Mickey]

in the software which I use, (Solidworks), there is no need to use layers. Layers is, I believe, more of a 2D Autocad thing. In my software, I drag and drop the solid model onto a pre formatted "Drawing sheet" and it automatically creates what views I ask it for. I'm not sure how you would do it. Does the program have a "Help" file associated with it?---Brian

Hello Brian, I will check. BobCad does have layers and I have just had a play with the colours as recommended and here is the updated image.

I will search now you have given me a lead...will let you know. It would be great if it worked like yours......

Mike

 

[Metal Mickey]

Well I have decided it won't be self starting in version 1 (This one) but if it works I will use self starting as the reason for next development. Anyway I think theres enough here for comments before I do the line drawings. The only way I can see I can do them is in profile with just the outlines. Unless some one tells me different?

Anyway a couple of images. One with the transparent feature. I have added different colours and it does help so thanks for the idea.

 

[44-henry]

Your drawings look pretty good. I have had very little experience with Bobcad; however, I use AutoCAD 2008 all the time. In this program I typically work in 2D and 3D simaltaneously when I'm designing (or re-drawing) parts. 3D is quicker I think and I always seem to spend most of my time in the 2D side where the small details are what usually takes the extra time. In the end I try to blend the two together like the drawings that I have attached shows. The tap wrench is a project that I plan on using in a manufacturing processes class that I teach at the university where I work. The different colors are an image of the bone and charcoal color case hardening we do in our lab that I mapped onto the 3D object.


View attachment Tap Wrench Page 1.pdf

View attachment Tap Wrench Page 2.pdf

View attachment Tap Wrench Page 3.pdf

 

[Metal Mickey]

I haven't given up on the design and build of a wobbler as shown with the 3D drawings I produced via BobCad. However I have been giving a lot of thought about whether I really want to do CNC in the future and the answer has changed really, I don't want to pursue CNC in the immediate future.

So I have decided to sell the software package and training video set on eBay http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MESELX:IT&item=380099174505

I am going to build the engine drawn in 3D and then make a set of drawings from the build. Wrong way around I know but then that seems to be the best way froward for me. Time will tell as always.

 

[Metal Mickey]

I should update you all as to where I am with my learning CAD and my own engine design. Not very far I have to say.

I bought, at great expense, for me , BobCad CAD software. They seemed far more focused on selling than supporting as far as I was concerned and whilst I did like there 3D side it was transferring the models to 2D drawing sheets that I couldn’t sort out. Without answering my many request and being fed up with the sales people who were told my views on support (they promised to pass on my remarks and help request) I could get no where.

As someone once said if you keep banging your head against a wall you eventually find out that it hurts! In the end I took the salesman’s advice when purchasing BobCad “you could always sell it on eBay as its all yours” (yes he did!) I did just that and listed it on eBay. I did not recover all my costs, but the biggest part, so looked for a cheap 2D drawing package. My confidence in software salesman taking a large knock I decided I would not go for such an expensive solution since I have cooled on the idea of CNC.

I saw a version of TurboCad 14 deluxe on eBay for under £30 so sent off for it straight away. When it arrived with a full training support CD system I thought it was a bargain. It would certainly do all the 2D stuff I wanted but it also does 3D. Whilst it is not as good as BobCad for 3D modeling it was only around a tenth of the price! So I then started to learn a whole new program. When it came to doing some of the tasks I wanted after becoming slightly more proficient, I discovered the natural limitations of the deluxe version. When searching out forums, the internet in general it seemed that upgrading it to a premium version was the way to go(where have I heard that before!) however I wasn’t going to fork out several hundred pounds again but I found an American supplier of TurboCad version 12 premium for about a $100 or so and that’s what I have now. I shall sell the version 14 deluxe soon so if anyone’s interested then email me.

I am now going to put all my efforts into learning how to use TurboCad 12 premium and have already produced some plans for small items in the workshop. At present I am working on a tool height setting fixture for setting the diameter of an in line boring tool (need it for the Seal build – link) based loosely on another’s design. A plan of the ball turning tool I made for the chess set featured in Model Engineer magazine (issues 4345, 4346 and 4347) to accompany a build article that may be published some time in the future.

So you see the engine design is going to be later in the year before real progress is made. Indeed it may be a case of building parts, that will be drawn up later, and others that may be drawn first. Something I may not be alone in doing……Experience and a better understanding of CAD may lead me away from this approach……..time will as ever, tell!

 

[Maryak]

Mike,

I have TC14 deluxe and I understand your frustration on both its' 3D capability and the price to upgrade. I am trying Alibre design which I downloaded free and eventually I hope to nail the 3D demon and find a use for both.

Good luck with your CAD - Once I got the hang of it I found TC to be a very good 2D program.

Best Regards
Bob.

 

[Metal Mickey]

Bob, I tried to download Alibre some time ago but failed miserably. Does the free version allow you to dump the 3D work into a 2D or engineers plan format? Mike

 

[stevehuckss396]

Bob, I tried to download Alibre some time ago but failed miserably. Does the free version allow you to dump the 3D work into a 2D or engineers plan format? Mike

Hi Mickey!

All of the work that i sent you for the Seal camshaft was done in Alibre including the 2D drawings. I have been using the free version for about a year. If i ever hit the lottery, I would buy the big money version. It works very well.

 

[Metal Mickey]

Hi Mickey!

All of the work that i sent you for the Seal camshaft was done in Alibre including the 2D drawings. I have been using the free version for about a year. If i ever hit the lottery, I would buy the big money version. It works very well.

Oh dear Steve, youv'e now given me a problem! What to do, what to do? I may give Alibre one more go before I decide to stick with one and at least learn the basics......some of the BobCad work has transferred across so its not a total loss but stickability needs to happen soon..........One more go..........

 

[NickG]

Alibre is fantastic although the free version is quite limited. I would love the full version but just can't justify the price.

Nick

 

[putputman]

Question for some of you that are using Alibre????

I have been using 2D for some years, but never tried 3D. I have recently downloaded the free version of Alibre. You get a full blown version for 30 days and then either have to purchase it or loose it and end up with the limited free version. I have no intention of ever purchasing an upgrade & have made that clear to the salesman.

I have been struggling with it, (haven't even completed the first exercise after several tries), and am wondering if it is worth the time and effort to learn this program based on the limited free version. Can the free version be useful in model making? I had hope I could make simple assemblies to show fits and interferences with this program.

Another question: Are there tutorials in the free version or do you have to master the program in the first 30 days.

 

[stevehuckss396]

I have been using the free version for a while. I have designed 2 engines from scratch. One being the Co2 V8 from last month and the other was a cox .049 based 9 cylinder radial.

The current Peewee project was drawn because i could'nt make sense of some of the numbers on the drawings. After drawing the parts I found some interference errors regarding the block and crankshaft. They were easily fixed before the first chip was made.

I would consider the time spent "worth it"