do you know of any good engineering/design forums?

[Mr Science]

I'm engaged in some projects I'd like some feedback on - and it struck me that it's likely well out of scope of a forum such as this - i'm sure there are qualified folks on here but does anyone know of any forums where such opinions would be more the norm ...?

i guess ideally you'd want a forum where engineers actually have tooling and production experience as how you make something and it's design are intimately related (seems to me) ...

 

[Milland]

There's a huge range of experiences here, so I wouldn't hesitate to put forth questions for this group.

But if you want a more engineering-oriented forum, try Eng-Tips Engineering Forums or check out Top 40 Engineering Forums & Message Boards : Scientia Blogger

 

[DMF_TomB]

I'm engaged in some projects I'd like some feedback on - and it struck me that it's likely well out of scope of a forum such as this - i'm sure there are qualified folks on here but does anyone know of any forums where such opinions would be more the norm ...?

i guess ideally you'd want a forum where engineers actually have tooling and production experience as how you make something and it's design are intimately related (seems to me) ...

.
designed for manufacturing. that is part is designed to be easier to manufacture. some techniques are old over a hundred years but other methods are changing with advances in tooling and fixturing. many free catalogs will show new technology like cutting tooling and fixturing cause obviously they want to sell you stuff.
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but be aware just cause a tool will go 30 to over 100 ipm does not mean your machine has the horsepower to do it or you can hang on to the part or excessive vibration becomes a problem.
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usually got to be able to calculate hp required and expected cutting forces. many vises,chucks and fixtures and even the parts themselves can not take tons of force without problems happening
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how you make a part on a 1.5hp machine and how its done on a 15hp machine can be quite different
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some machines like laser and water jet cutters werent around 100 years go. often they have catalogs showing what they can do if you can afford to buy the machines

 

[BugRobotics]

Just as Milland stated, feel free to drop a question. Just make sure your title is descriptive and it's in the best place you can put it in the forum ("General" is good catch all if you don't have something specific to any other category).

Most questions, no matter how esoteric, generally receive quality answers on this forum. So...what's the question(s)?

 

[Mr Science]

thanks - i was just ruminating over placing a bearing (as a very very light duty pulley) on a 5mm shaft with circlips vs machining a new 2 part shaft that would seat the bearing much more substantially - it's a manufacturing gig so i guess cost and time certainly factor into the design! But i was just second doubting myself a lot as to which way to go and figured it might be nice to have some feedback ...

 

[MattiJ]

Just as Milland stated, feel free to drop a question. Just make sure your title is descriptive and it's in the best place you can put it in the forum ("General" is good catch all if you don't have something specific to any other category).

Most questions, no matter how esoteric, generally receive quality answers on this forum. So...what's the question(s)?

As long as its not any sort hobby sized machinery related.
Or you need have exceptionally thick skin or really well thought out questions.

 

[themedulla]

thanks - i was just ruminating over placing a bearing (as a very very light duty pulley) on a 5mm shaft with circlips vs machining a new 2 part shaft that would seat the bearing much more substantially - it's a manufacturing gig so i guess cost and time certainly factor into the design! But i was just second doubting myself a lot as to which way to go and figured it might be nice to have some feedback ...

You would be surprised at how much load a circlip will take before unseating. You could also use shaft collars to keep it in place if you don't need to be very accurate with positioning (and there is clearance for the collars).

 

[BugRobotics]

thanks - i was just ruminating over placing a bearing (as a very very light duty pulley) on a 5mm shaft with circlips vs machining a new 2 part shaft that would seat the bearing much more substantially - it's a manufacturing gig so i guess cost and time certainly factor into the design! But i was just second doubting myself a lot as to which way to go and figured it might be nice to have some feedback ...

Do you have a sketch of the design? What kind of loads will the shaft/pulley see? Shaft material? Is there any preload applied to the bearing through wave washers or similar between the two clips (I ask because you'll likely have some wobble if not)?

 

[Guest]

Also what materials are we talking and what environment will the shaft be exposed to? Is the bearing a slip fit or press fit?

 

[Mr Science]

well there are about TEN different designs I guess i could come up with in a pinch but nothing i particular - so i haven't really sketched anything out - the simplest being simply two circlip notches adjacent to a roller bearing - the shaft material is probably 304SS. The application is for a tape guide for a set of archival 1/4" tape machines for transfer - so the load is ONLY the tension of the tape but I would like to stay away from magnetic materials for the bearing itself and have some sort of 'guide' next to the bearing itself so the tape stays put - so lateral load on the circlips should be just about zero ... though clearly i have to think this out more as I'll probably go with the guides now that i think about it - and maybe the snap rings holding those in - or else have them held in place via threaded assembly of some kind ... i didn't quite want to get into the details yet because I haven't got in to measure the shafts etc yet ...

 

[Dumpster_diving]

Reverse engineer from an existing reel-to-reel tape player maybe?

Avoiding magnetic materials would seem like a requirement. Possibly even some static discharge feature. Perhaps combined with a felt wiper to keep the guide clean. Loads are miniscule as you say but alignment and lack of abrasion would seem to be a major consideration. Circlips without a press fit on the bearing ID are going to allow some wobble.

Perhaps your 304SS shaft with a press fit bearing onto which a press-fit custom delrin pulley (with it's own alignment flanges that rotate with the pulley)?

Again, starting off mimicking an existing design would seem to be your friend.

 

[DDoug]

Reverse engineer from an existing reel-to-reel tape player maybe?

Avoiding magnetic materials would seem like a requirement. Possibly even some static discharge feature. Perhaps combined with a felt wiper to keep the guide clean. Loads are miniscule as you say but alignment and lack of abrasion would seem to be a major consideration. Circlips without a press fit on the bearing ID are going to allow some wobble.

Perhaps your 304SS shaft with a press fit bearing onto which a press-fit custom delrin pulley (with it's own alignment flanges that rotate with the pulley)?

Again, starting off mimicking an existing design would seem to be your friend.

Yup.

Why not just grab what you need from some scrap machines ?

1/4" reel to reel machines come up all the time at auctions,
and I'll bet someone has a stash of NOS parts.

FWIH, the 2" r-r are still being kept running in some recording studios,
new tape is still being made Eastern Pa.

 

[Mr Science]

yes - that's mostly what i'm doing - taking ideas from existing machines - the machines the client (a friend) has are very finely made swiss machines but theres a tape guide that's just a 5mm rod - so i was thining maybe to use this to press fit a 628 (IIRC) bearing onto (and secure with circlips) but I have to work on a way to prevent slippage - and I suppose I can copy the existing design (pulley) for that part ... so basically we're building pulleys where only guides existed before .. anyway thanks

 

[lionelt]

Bearing fit tolerances.

https://www.nskamericas.com/downloads/americas_bearing/e126 Miniature Ball Bearings.pdf

 

[leswatts]

I'm an engineer. I'm also involved in audio...I own a microphone company. Lots of machining.
Are your machines Studer?

Ball bearings are usually not used on tape transports because they rumble. Oilite porous bronze is a better choice. I would use something harder for the shaft than 304ss. The pulley/guide should be something completely non magnetic like aluminum. 304 can be slightly magnetic so it's not a good choice.
Les