profile framing systems 5

[HDS]

I need the opinion of the ENG-TIPS community. What is the best T-slot Aluminum profile framing system?

I am in the US and want to build benchtop size products in low volume. There are several systems out there (80/20, Maytec, Minitec, Parker ...) They all seem to be proprietary and do not interchange. So I will be stuck with which ever one I choose. Is there a standard from someone like SAE, ISO, or ANSI that has interchangeable parts?

What are the differences you have seen between vendors?

Why do you use the system you do?

Are there any issues to look out for that may not be obvious until you get into construction?

TIA

 

[SincoTC]

We use T-Slotted extrusions for a low volume benchtop product and have had a number of issues; I won't name the manufacturers as I'm fairly certain that they don't supply the US market. The only approach to standardisation I've encountered is the section size and T-Slot width; the slot profiles and hence the nuts vary, even with the same manufacturer, where the thickness of the top of the slot is different on the same sections, according to whether light or medium duty.

The main deciding factor for us, was that we wanted a neat Butt-joint between the Vertical and horizontal members of a visible frame; so we chose one that did both 45mm and 40mm sections, this meant that the smaller section of the horizontals sat square on the face of the larger verticals, between the adjacent corner radii. Whereas, had they both been the same size, it would have left an ugly dirt-trap (I hope you can follow that)!

The issues we encountered and important things to consider are as follows.

1/ Surface finish, will it be visible? If so, the finish needs to be consistantly good and free from scratches and dents, this is much more important if it's for a finished product that you want to put your name on, than if it's for a storage rack! There's very little that you can do with a damaged anodised surface that won't make it look worse!

2/ Will you get them to supply it cut to length and how accurately can they do it? The first few batches we got were done on their brand new CNC saw and were brilliant, but then the blade was replaced (or badly re-sharpened) and it started pushing off, so it was no longer square and the lengths varied. If you do need it to be accurate and square, and especially if you need to do any machine work on it yourself as we did, then get it a little longer and finish the ends square and to length yoursef when you do the machining. It will be cheaper if you can relax the cutting/squareness tolerances, you're in control of vital sizes and YOU can take care to keep the vise jaws clean and not to embed swarf into the visible faces (Arghh)!

3/ Finally, choose a system that has well designed and rigid brackets and a clever method of joining the elements, preferbly something that "Pulls" the faces together and just doesn't rely on the friction of grub screws, which will surely open up in use (if not on tightening and handling)!

 

[HDS]

Thanks SincoTC

I have gotten the impression that differences in customer service maybe more important technical differences. That is one reason I am nervous about getting locked into a proprietary product.

I understand what you are saying about the joints. The details of corner radi are not something I had thought of yet.

Does anyone know if there is a mil standard that these things fall under? That is always a good source of stable standardized parts.

Many industries seem to have their own versions of these framing systems. For example signs, and retail displays.

 

[imcjoek]

Many of the 80/20 and Maytec bits do interchange, since the slots are at least of similar dimension. We usually prefer the Maytec stuff for large frames since the joints seem to be stiffer. For tabletop assemblies I don't know that that matters, so talk to local distributors about delievery and pricing.

 

[HDS]

What is it that makes the Maytec joints stiffer? better fasteners? Better fit? Easier to tighten?

 

[chicopee]

Is this for Jigs and Fixtures?

 

[SincoTC]

You're right HDS, customer service IS important, especially if you need a finished product that looks good and has to stand up to close inspection. We do admit to being a bit "picky" when it comes to tolerance and appearance of the profiles we use, but only because some of it is highly visible and forms part of a moderately expensive piece of scientific equipment, and we care passionately about how it looks and fits together, although, where parts are out of site we are a little more relaxed.

My impression is that most of these systems seem to have been developed to make production line handling equipment, fixturing and racks, where the end users were not too fussed about appearance or actually adding the odd scratch or dink! So the care in handling the profiles was scaled down to suit. However, the situation is improving now the systems are finding their way into Clean-rooms and Workstations and Etc, where expectations are higher, and they are now happy to individually wrap the parts if specified on the order.

There doesn't seem to be much incentive to standardise; it's far better for them to lock the customer in with non- interchangability. They all make claims for better fittings and easier assembly than the competition, so we got the Rep's in with their little cases of goodies to get a feel for what was on offer and what was better engineered.

I don't know of any Mil standards in the UK, but you may care to have a search here:

http://www.nssn.org/

 

[HDS]

chicopee

My product is much like SincoTC's a low volume expensive piece of equipment. It needs to look good but the money needs to be spent on the hardware inside not the cabinet. The framing systems are attractive because of the design flexibility they provide.

SincoTC

I didn't have my hopes to high on finding interchangeability. Standardization usually only comes about when a very large entity like a government or a car company demands it. Sometimes several small guys will get together but that is much more common with software than hardware.

 

[moltenmetal]

Whether or not they sucker you with a low cost for the profiles themselves, they ALL kill you on the hardware. You pay a LOT for the convenience of using their complete, pretty, pre-engineered system.

UniStrut is a lot cheaper, but nowhere nearly as pretty or as versatile.

I'm waiting for the Chinese mass-produced knock-off myself. It's inevitable, but if it's on the market I haven't discovered it yet.

Minitec has the advantage that an ordinary 5/16" square nut not only fits in the slot but can be dropped in from above- no need to buy their expensive, flimsy drop-in nuts.

Whether you want to build your own brackets from aluminum angle (basic woodworking tools are all you need) or build from their catalog depends on your labour cost and how much the "pretty" factor is worth on your units.

 

[MintJulep]

Some years ago when I actually designed things for a living we had a project where we started out by designing welded square tube steel bases and frames. The fabricator quotes for these came in astronomically high, and our bean counters started looking for options.

They came up with the Bosch extruded aluminum framing system.

http://www13.boschrexroth-us.com/aluminum/framingcatalog.asp

Our local distributor offered the option of taking our existing welded frame prints and providing us fully built dimensionally equivalent aluminum frames. Even with the value-added services they were less expensive than the steel would have been.

Things worked out fine with the framing (not so with the rest of the equipment unfortunately).

At any rate, after that project we started designing from scratch to use the Bosch framing.

 

[lumenharold]

It may or may not be a consideration for you (it is for us) but having 3D CAD files available in the software format that you use saves a lot of engineering time. I'd rather spend the time designing the unique equipment we supply than detailing a purchased part.

For In-house equipment we have had great luck with 80/20 garage sale (ebay) stuff. Most is like new or is new and works fine but is way less expensive. Just my two cents....

Harold
SW2009 SP2.0 OPW2009 SP0 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600

http://www.lumenflow.com

 

[drawoh]

MintJulep,

I have designed a couple of welded steel frames, including a small 19"[ ]rack, and they were fairly cheap. Weldments require careful design and preparation of drawings. Otherwise, the sky is the limit.

My racks, with all the bits and pieces we wanted added to it, were around $800 Canadian. What do you mean by astronomically high?

JHG

 

[MintJulep]

drawoh,

Too many years ago to remember actual numbers.

This was substantially bigger than 19 inches. More like 50 feet long, three feet high and a foot wide.

We probably had unrealistic expectations for straightness and flatness of the working surfaces as well.

 

[drawoh]

MintJulep,

You got me with the fifty foot length. Welding cannot be the only fabrication method on something like that.

Also, you have to design around the sloppy welding tolerances. If you can do it right, there is little or no assembly of your frame, on site.

JHG

 

[HDS]

SincoTC

Do you have an open frame or do you put panels on your product?

Do you have to deal with EMC testing issues to CE specs?

lumenharold
Solid Edge is good enough at handling imported data that steps files will be fine for this kind of stuff. However, it does not have one of the nice software packages dedicated to structural framing system. It is certainly a requirement that 3d models are available for every part. (it is nice to say that all most all vendors realize this for any kind of part these days.)

 

[SincoTC]

HDS,

It's a mixture really; an open frame with all of the end verticals (fitted with levelling feet) and a couple of the horizontals visible and prominent, but the rest of it is boxed in with with a CNC-routed and folded "Tub" of pre-finished Aluminium/Plastic composite (as used in signage and display industry). The extrusions afford secure mounting for the moving elements of the device and a "load path" for the transit mounting plates. The tub adds stiffness, a "clean" exterior and reduces the impression that it was just put together from off the shelf parts.

Our first prototype was entirely extrusions and used a lot of the chosen system's panel and beading, but it did look a little too much like it was something that the users Lab Technician could make up, also it lacked the stiffness we desired, mainly because some of the nicer joint designs and panelling were not then on the market.

We now use the type of extrusions that have one or more faces without the T-Slots to give a clean exterior surface where they show and this is where, without the slots to break up the surface, the importance of a good anodised surface is significant.

Yes, we do have to comply with EMC testing and specs; we tap extra holes in the T-Nuts so we can fix the nut in place with knurled point set-screws that "bite" through the insulating anodised surfaces, this way, our non-anodised brackets form a grounding pathway for all the extrusions, this is checked for continuity/resistance during assembly and we use bonded straps across removable or hinged panels.

 

[HDS]

Sinco

It sounds like you really have all the details covered.

I was thinking about similar materials and methods and it is reassuring that they have proven successful for you.

Thank you,

HDS