Hello Guest it is March 05, 2021, 09:53:02 PM

Author Topic: Mach 3 Sewing Machine  (Read 26902 times)

0 Members and 1 Guest are viewing this topic.

Mach 3 Sewing Machine
« on: November 24, 2008, 08:33:56 AM »
Hi All

An exciting time.. Over the last couple of years I have kept an eye on Mach 3 from the numerous forum posts both here, the CNCzone and on You tube. Mach 3 has become irresistible.

I work in the rag trade so for me the use of CNC will be a little different to metal working or routing. My interest is in stitching, while the overall system accuracy for stitching is a lot less than precision machining. There are other problems that must be overcome. The system I intend to create will be in the form of large Router table. With the added complication that the sewing axis will require 2 synchronized drives to drive the needle and the hook and thread bobbin separately, (The mechanism under the table of the machine) a simple 1:1 ratio but not constant speed and with a speed range of 500 – 4500 rpm, and this speed must be relative to the tool path speed. Not an easy task from my enquiries so far.  Yes it can be done mechanically but not without a lot more hardware.

My previous experience was retrofitting a CNC sewer. It took a lot of time. The hardware had to be hacked to enable user programming rather than going back to the supplier it was encrypted, or rather obfuscated. (Not uncommon for textile machinery) I also wrote a VB program to feed it with code its native code not G code. The software reads a DXF file using polylines and converts it. The math routines may come in handy again.

Today I would chuck out the hardware and start again.

I would be pleased to hear from any fellow Rag trade members, it would be fun to discuss some of the issues that relate to stitching.

Cheers

John Mac

Offline RICH

*
  • *
  •  7,419 7,419
    • View Profile
Re: Mach 3 Sewing Machine
« Reply #1 on: November 24, 2008, 09:56:23 PM »
Hi John,
Welcome to the site. I haven't noticed  anybody doing anything applied to a sewing machine but
go ahead and post and see if Mach is an application which you want to use and learn more about. 
Your free to post in other threads now.
RICH

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Mach 3 Sewing Machine
« Reply #2 on: November 25, 2008, 05:15:24 AM »
There is one company that makes and sells sewing machines that run Mach, do a search for magic quilter and you may find something. I doubt if they will give you much info though as obviously it is a commercial venture for them but there are videos of it in action so it might give you some ideas.
Hood

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Mach 3 Sewing Machine
« Reply #3 on: November 25, 2008, 05:17:06 AM »
Re: Mach 3 Sewing Machine
« Reply #4 on: November 25, 2008, 08:05:52 AM »
Thank you Rich and Hood you guys are quick to respond!

I have been working on the calculations for the x axis.

It will need to be about 4000mm wide
Made from 2 lengths 250 x 150 x 5 RHS spaced 300mm and joined with 150 sq tube and the ends welded over and fully joined.

There will be 2 type 25 rails mounted on each beam giving 4 in total.

Compared to machining or routing sewing has the need to have a tool on the bottom and the top of the cloth hence the need for the large vertical O frame to pass the work through.

I calculated the deflection (Simply supported at the ends only) to be about .211mm with a 40kg load in the centre  (The moving head) and the distributed load imposed by the rails about 10 kg per metre.  The frame has to be really stiff the load is small but there will be resonance. I wish I had better software, and a younger brain.

Not bad for such a large span.

I used a handy tool to do a quick deflection calk called Beam boy.
I found it at:
http://www.engineers-international.com/freeshare.html
It works quite well I am sure there are more advanced tools so if you have one please post a link.

250 x 150 x 5 RHS weighs about 29.9 kg per metre add to that the rails and the sewing head and we are moving about 350kg to 400kg

For a standard 4000rpm sewing machine we need a feed rate of about 233mm per second max. That is a fair amount of weight to push around; it will need some meaty drives. (I think I will drive it in tandem from the ends). Unlike metalworking the positioning accuracy required is around .5mm, (approx 20 thou imperial).

The frame with the sewing heads not included there we need a couple of thou max error along the x axis.

Sizing the drives is not going to be easy for me. If there is software out there in cyberspace to assist I would really appreciate hearing about it.

Usually the first iteration of a new design is doomed to be changed, but so far its looking good.

Cheers

John Mac
« Last Edit: November 25, 2008, 08:14:17 AM by John Mac »

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Mach 3 Sewing Machine
« Reply #5 on: November 25, 2008, 08:22:47 AM »
Might be worth looking into the Alu extrusions for the machine structure, might find them by googling Bosch Extrusions, they are very rigid and lighter than steel for more strength and will allow you to use lighter sections. Problem is they are not cheap so might not be worth it.

Look up some of the servo makers sites, most have sizing software. Think Kollmorgan have some, servosizer rings a bell.

Hood
Re: Mach 3 Sewing Machine
« Reply #6 on: November 25, 2008, 09:52:39 AM »

 Hi Hood

The catch is for a given section size the Aluminium will be lighter but the deflection will be higher. Most of the time by the time you have the stiffness sorted strength looks after itself.  The depth of section would need to be increased to gain the same deflection number.

The other catch is the straightness of the material when I checked the steel supplier the straightness from the mill is specified as within the section length divided by 500.

That means 4000mm /500 = 8mm possible camber. That needs to be corrected before the rails are placed.

Unless the Bosch rails were perfect they would have to be machined also.

Careful inspection at the steel suppliers yard should find some better than standard. (If they will let you in!!)

There is a jobber near us that has an Elgamill I will have to contract out this part
http://www.factoryhub.com.au/DesktopDefault.aspx?ItemID=881026&TabID=202700
Gee I wish I had one of those, very nice.

The rest I can machine myself.

So the frame can be mounted and machined for the rails.

If straight stock is not available then 200x100*9  could be used to allow machining the mounting point That has a deflection of .159mm Still OK  and only 7kg metre heavier slightly better than the 250x150x5 section above actually.

Another way would be to weld thicker pieces on and machine those.

All these compromises are a bear.

Cheers

John Mac

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Mach 3 Sewing Machine
« Reply #7 on: November 25, 2008, 10:52:02 AM »
The Alu I am talking about is the Bosch Extrusions, not just RHS alu and also from the stuff I have seen it is very accurate. This is the stuff I got bits of when a local company shut their operation,  http://www13.boschrexroth-us.com/Framing_Shop/Product/Default.aspx?category=10109
  Dont know the cost but probably is quite high they used it in all of their custom inhouse  machines.

Hood
Re: Mach 3 Sewing Machine
« Reply #8 on: November 25, 2008, 07:12:30 PM »
Thank you Hood

The Bosch extrusions are nice.

Alas the straightness is not quite there.

http://www13.boschrexroth-us.com/catalogs/mge50/sections/section%2016.pdf
Page 2. Lengthwise profile straightness tolerance
That shows an error of around 2 mm using a 2 metre lenth, it would be a lot more using a 4 metre length.

Using the deflection calculator Bosch provide on their site. For a 4 metre length of 100 x 200mm section I got .39mm compared to the .159mm for steel (but overall a lot lighter frame)

Easy cheap and accuracy can never appear in the same sentence.

Still there must be another way: Maybe precision laser cut plates assembled into a box frame and welded?  Maybe with small slots cut in line with where the rail would sit to enable you to place the rail against the edge for location. The laser could cut the mounting holes as well.

Has any one tried that?

Cheers

John Mac

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Mach 3 Sewing Machine
« Reply #9 on: November 25, 2008, 08:16:04 PM »
Dont think ywelding would be the answer, not much hope of keeping accuracy if you were welding the seams.
Hood