better to use off the shelf linear guideways?
better to use off the shelf linear guideways?
(OP)


I've been happily working on a platform design as above (500mm long, 350mm wide, vertical angle-irons 450mm long; cylinder represents linear actuator). The purpose is to provide 300mm of vertical motion and carry a load up to 20kg (that could even be placed at the far end).
The rollers are mounted on a bolt with a flange, then washer, then cam nut, such that the platform can be aligned, compensating for any distortions in the welded frames of the support (not shown) and the platform itself. Have built one prototype and it all seems to work quite well. Still need to add some blocks to provide lateral stability.
A friend took one look at all this and said I should use linear guideways (such as Hiwin HG series). They are not cheap but he insists it will be cheaper than machining all the relevant components to make my setup work.
I had the impression that I was designing something pleasingly simple that would deal with the load whilst providing adequate stability; that ultimately it should be a cost effective approach.
So my natural reaction is to start thinking how to cut lots of plates with 20mm holes (for the cam nuts) efficiently, how to mill the nuts without finishing passes to do so fast, how to turn the bolts quickly etc. and so forth. Is it just obvious that my friend is right and should go with prebuilt linear guideways?
Would anyone like to chime in on this matter?





RE: better to use off the shelf linear guideways?
When you use OTS components, someone else already figured all this stuff out. That is what you are paying for.
Then there's the controls. Are you going to design and build controls? Is that going to cost less in terms of time and money? If it is then you are a savant and working in the wrong field.
RE: better to use off the shelf linear guideways?
Items like Hiwin HG guides have a lot of extra precision that didn't seem warranted here (purpose is to lift a container of food up and down) and so the naive hunch was that in the end (after making a couple of hundred?) with OTS guides might be paying for something that we didn't need?
RE: better to use off the shelf linear guideways?
RE: better to use off the shelf linear guideways?
As @TheTick mentions: they've also the benefit of dedicated design minds inventing the best way to solve that niche issue. When possible, use OTS components. You're not a lesser designer for it. You're not a better designer for reinventing a wheel. You're a smart designer, using your boss's money more frugally, to get good performance from less investment. The novelty of a design task like this is not in how 'customized' it is but rather in its performance and arrangement.
Something that is only 10% beyond design requirements can easily be 5x the expense of something that's 100% beyond design requirements.
There may be more affordable linear rail systems. There are a good number of styles out there. Don't stick to the one brand or product style. You might find something that doesn't look like lipstick on a pig, if that's what you fear an expensive rail will seem.
RE: better to use off the shelf linear guideways?
I need to find a lower precision / robust OTS solution.
My suppliers have more precision type CNC linear guides which are overkill.
Will now start looking further afield. Trying to find the right search terms so that don't end up wading through lots of higher precision stuff....
RE: better to use off the shelf linear guideways?
RE: better to use off the shelf linear guideways?
No affiliation, just like their products.
RE: better to use off the shelf linear guideways?
RE: better to use off the shelf linear guideways?
http://www.bwc.com/
http://www.pbclinear.com/
RE: better to use off the shelf linear guideways?
RE: better to use off the shelf linear guideways?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: better to use off the shelf linear guideways?
RE: better to use off the shelf linear guideways?
Cheers
Greg Locock
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RE: better to use off the shelf linear guideways?