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PostPosted: December 7, 2011, 8:47 pm 
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Hey everyone,

I am starting to design my own frame for a custom super car I plan to build from scratch and I wanted to determine the costs of various methods. I would obviously prefer the ability of laser tube cutting due to its precise nature and the fact that I can drop off a cut list in solidworks and pick the tubes up and know they will all fit together.

I did a search and came across only one person who used laser tube cutting and had a price listed, he had a frame cut along with a MDF chassis jig and said the cost was $7,000 which seems pretty insane(but maybe it isn't?).

Obviously it likely depends on how long of a tube they can load to minimize having to switch tubes frequently but these lasers cut so quickly it still seems hard to think $7000 is a competitive option. It seems like you could even pay someone way less to cut and then tube notch them by hand and come out way less than that even at $100 an hour.

maybe the price is skewed by the MDF jig added cost but I doubt that is a bulk of it.

Anyways, my point is all of these are assumptions on my part, has anyone actually gotten quotes for cut lists for their frames? I have yet to fully model a frame and make one so I wanted to check here first.

thanks for the help!

Ben


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PostPosted: December 7, 2011, 11:38 pm 
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I recently had Marks Brothers (in Boring Oregon) give me a quote. You are right, there is a set up fee for each tube size. I shared with them what I was doing and what I wanted (including each tube etched with a letter code and some tubes marked with a centerline). For a tube count in the Locost range, the cost came out to a little over $7.00 per tube (plus steel). That is far better than my wages. They're about 15 min. from my shop, so no delivery costs were included. I have since had them cut several misc. brackets and I've been happy with their service and quality.

One of their videos... http://www.youtube.com/watch?v=UeGVbtrrHjE

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PostPosted: December 7, 2011, 11:45 pm 
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RS7 wrote:
I recently had Marks Brothers (in Boring Oregon) give me a quote. You are right, there is a set up fee for each tube size. I shared with them what I was doing and what I wanted (including each tube etched with a letter code and some tubes marked with a centerline). For a tube count in the Locost range, the cost came out to a little over $7.00 per tube (plus steel). That is far better than my wages. They're about 15 min. from my shop, so no delivery costs were included. I have since had them cut several misc. brackets and I've been happy with their service and quality.

One of their videos... http://www.youtube.com/watch?v=UeGVbtrrHjE


This is great info! When you say $7.00 per tube do you mean per cut tube they they do? If so how many tubes make up the average locost frame?

How large of cutter do they have, as in can they load only 10' tubes at a time or 20'? Just trying to gauge what to expect when I try for quotes locally to make sure they aren't screwing me over. :)

$7.00 per tube seems very reasonable, even better than I thought.

Thanks for the help.

Ben


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PostPosted: December 8, 2011, 2:10 pm 
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SpecBC wrote:
This is great info! When you say $7.00 per tube do you mean per cut tube they they do?

Per complete tube, i.e both ends cut.

SpecBC wrote:
If so how many tubes make up the average locost frame?

I haven’t counted the common frames, but I suspect my count may be a little on the high side… I used 160 for quote purposes. The set-up fee was nearly a quarter of the burn costs, so a different tube count can have a large impact on cost per tube.

SpecBC wrote:
How large of cutter do they have, as in can they load only 10' tubes at a time or 20'? Just trying to gauge what to expect when I try for quotes locally to make sure they aren't screwing me over. :)


It was an odd number. 24’ stock sticks in my head for some reason. I know it was over 20’. It’s also self loading. You can find youtube videos of their machine auto-loading from the rack behind it.

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PostPosted: December 8, 2011, 11:09 pm 
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So it's $7 a tube in lots of 160? That's what, four Locost chassis or so? And the coding (the translation from the drawings you supply to whatever instructions the laser reads) is included in that? Sounds interesting. It sure would make it easier to do round tube frames.

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PostPosted: December 8, 2011, 11:48 pm 
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I find it hilarious they charge for tube changes when it automatically does it, but obviously I understand it's a business and they have the right to charge since if it wasn't automatic they'd be paying someone to change it anyways.

I think once I model my frame I'll have to send it over to them for a quote.

If anyone else has places they have gotten quotes from or recommend please let me know and post the info.

thanks again for the help.

Ben


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PostPosted: December 9, 2011, 12:46 am 
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SpecBC wrote:
I find it hilarious they charge for tube changes when it automatically does it...
It's not a matter of a "right to charge", it's a matter of earning back their capital investment in the tube changing apparatus. I'll bet their loading charge is less than what you'd pay if they had a guy loading tubes and setting the tube alignment by hand; either the machine has to be paid for, or the labor has to be paid for, and they wouldn't have invested in the automatic equipment if they didn't think it would be some blend of faster and/or cheaper than loading the old fashioned way. But it's still not free nor instantaneous, and when tubes are loading, the laser isn't burning, and thus the laser and its operator aren't making money--or even covering their overhead--by cutting tubes.

They can cut one 24' tube into 24 11" pieces more quickly than they can cut 12 of those tubes into 24 11' pieces--they're the same amount of work for the laser, but the second job is a dozen times more work for the loader so the job takes longer, and time is money in the manufacturing biz.

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PostPosted: December 9, 2011, 1:07 am 
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It sure would make it easier to do round tube frames.


It changes the frames you make too. What the joints can look like etc. At least in terms of the effort, complicated joint would be a lot of work by hand. This could make little weld in ears so you can fit the joints together etc. , does that make sense? A piece of fish mount that's cut off and can be welded back on during assembly.

The concern that's been expressed before here is that once your average person starts welding, not all the tubes will fit as the build progresses. I wonder. It's very attractive to be able to flat ship a frame. This has to be cheaper then paying someone to do the work by hand.

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PostPosted: December 9, 2011, 1:32 am 
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JackMcCornack wrote:
SpecBC wrote:
I find it hilarious they charge for tube changes when it automatically does it...
It's not a matter of a "right to charge", it's a matter of earning back their capital investment in the tube changing apparatus. I'll bet their loading charge is less than what you'd pay if they had a guy loading tubes and setting the tube alignment by hand; either the machine has to be paid for, or the labor has to be paid for, and they wouldn't have invested in the automatic equipment if they didn't think it would be some blend of faster and/or cheaper than loading the old fashioned way. But it's still not free nor instantaneous, and when tubes are loading, the laser isn't burning, and thus the laser and its operator aren't making money--or even covering their overhead--by cutting tubes.

They can cut one 24' tube into 24 11" pieces more quickly than they can cut 12 of those tubes into 24 11' pieces--they're the same amount of work for the laser, but the second job is a dozen times more work for the loader so the job takes longer, and time is money in the manufacturing biz.


Right I wasn't trying to say they couldn't make money which is why I said they have a right to charge because it is replacing having it manually done, hopefully there is a discount for it, it was said that is was 1/4 of the cost. I have to assume they must do it(charge) in a very quantifiable way, maybe on a per min basis for the whole job including changes or maybe just based on how long the laser is on? I'm not sure but it would be interesting to know that stuff.

Either way seems like a very viable option so that is exciting.

Ben


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PostPosted: December 9, 2011, 9:13 am 
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horizenjob wrote:
The concern that's been expressed before here is that once your average person starts welding, not all the tubes will fit as the build progresses. I wonder. It's very attractive to be able to flat ship a frame. This has to be cheaper then paying someone to do the work by hand.


If this was the case and you already had all the tubes pre cut i don't see why you would not tack the whole frame together before final welding. This would minimize any warpage causing fit up issues. Also with this method the rigidity that was designed into the completed frame would help to prevent warpage and distortion issues. I would even go as far as including temporary tubes such as one to be tacked in as a diagonal across the engine bay that would be removed after welding was complete.


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PostPosted: December 9, 2011, 9:48 am 
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horizenjob wrote:
At least in terms of the effort, complicated joint would be a lot of work by hand.


I find tubemitre.exe terrific ...

http://www.ozhpv.org.au/resources/shed/tubemiter.html

...a paint marker, a cut off-saw to take 95% off in 2 cuts and a little grinding and you're there. I wonder if some realize it only needs 2 cuts to make the bulk of a fishmouth?

I'll take some pictures next week of the process to show how easy it is to encourage others.

horizenjob wrote:
This has to be cheaper then paying someone to do the work by hand.


Cheaper still if you do it yourself and very satisfying too!


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PostPosted: December 9, 2011, 10:03 am 
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RS7 wrote
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You are right, there is a set up fee for each tube size.


To me that means that they separate all tube sizes (material, diameter and thickness) as separate runs; not lengths and cut details. It makes sense to me as different tube sizes require different feed rates and possibly power levels. This may not mean a charge for each tube loaded into the cutter. Although you will be paying for loading the machine whether by auto-load or by hand.

According to their website,
Quote:
True high production capabilities are achieved with loading full bundles of tubing.


I doubt if 20 pieces of 24 foot tubing qualies as high production. They would probably hand load that job. But I may be wrong.

I was told that, in the early days of CMC, they sold flat kits for the builder to assemble and weld at home. That turned out to be a bad deal as things usually warped during welding (by us amatuers of course).

With the number of variations in chassis designs being built here on Locostusa.com, I doubt that more than 2 or three would use the same frame. With different chassis sizes, uprights, engines, rear ends, control arm variations and such, the design permutaions escalate almost infinitely. It may not make sense to have more than one chassis at a time. Then add the CAD time (read $) involved to get an accurate cut list for the laser cutter to start with, the cost will skyrocket. And what if you made a slight calculated error in your CAD Model? There gose a couple thou. Now for a builder who is building 5-10 kits of the same design in a year, this makes a lot of sense.

I used Tubemiter and a cutoff wheel in my HF grinder for the round pieces and just a the cutoff wheel for the square tubes. Quite effectively.

For a one-off frame, if you are trying to save time and are willing to swap out your money for that time, you may be better off just buying a completly welded frame.

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PostPosted: December 9, 2011, 3:20 pm 
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Part of my senior design project was to be the first FSAE team at my school to implement laser cut tubing (about 90% of the needed tubes) in place of 100% hand fitting. If you have the money it is sooo freaking worth it. We cut a 3+ month build down to 5 days with 3 guys. You do need to invest in some serious jigging though.


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PostPosted: December 9, 2011, 3:36 pm 
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I think the ability to make a frame self-jigging would be the main advantage of laser cutting. Leave little spikes on the cut-off ends of tubes that butt up next to other tubes (e.g. the vertical tubes that hold the top and bottom frame rails apart) and cut holes in the tubes they butt up against (e.g. the frame rail tubes) that the spikes would fit into. That way you wouldn't need to measure where the joints go--it'd be like assembling an IKEA computer hutch (except you'd weld it instead of bolt it).

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PostPosted: December 9, 2011, 3:39 pm 
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WelderLee, including some jigging or additional support in the kit is a great idea...

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