Can someone build me the following...

Ok, here's a list of the parts you've requested:

12 bars (4 rows, 3 in each row), with knobs on them. Motor with a speed control Height adjustment mechanism for bars

In addition to the parts you requested, there's a few more things you'll need:

The motor will need gears and/or reduction to attach to the bars.

The height adjustment mechanism will be controlled by a separate motor (unless you want a hand crank?). This is additional gearing, another motor, and more brackets.

Have you thought about the size of the knobs and how big they will need to be to feel it, yet not catch on the material you're massaging? Remember, there's a lot more pressure on the seat than the feet.

Also, the weight of the person sitting in the chair affects the torque (and speed) on the motor... so either you stick with a cheap voltage-controlled speed, or get a more expensive and complicated controller where the speed is more constant, regardless of who's sitting in it.

Do you want quiet motors like the ones already in your chair (more $$$), or can you put up with louder motors?

Do you plan on powering the 2 extra motors from a wall outlet, or the chair's internal power supply? If it's the latter, this might cause an overload on the chair's PS.

In other words, I don't think you fully understand what you're asking for.

Dave

Your right, I don't fully understand what I need. That is why I am need someone with experience to build it. Someone who is aware of all of the items you mentioned. I am not sure what motor and gear casing to buy along with a number of other things. Your also right about the weight of me sitting on this thing. That is why they haven't already done this. They can never be sure that some huge person won't plop themselves into the chair and break the seat part. But if I have it build I will just have to be very careful when sitting down. Or I was thinking that of a switch that moves the rollers down when there is no preasure in the chair and then you have to bring them back up to apply preasure when sitting down. Also maybe using air to raise it up and down. I would buy the same rubber bumps that they put on the foot part for the seat part. I can buy these through the chair manufacture. But I don't want to spend time and money on trial and error. Even if someone could design it I could probably built it. I plan on owning this chair for a long time so it will be worth the investment to add this device to it. Thanks for the feedback. Russ

Russ-- just to put an order of magnitude on it for you--you're talking about a project whose cost will be measured in thousands or even tens of thousands, not hundreds, of dollars. Even then, you're going to have a prototype, not a finished product... good luck.

Yes. Russ, when I said I didn't think you fully understood what your request implied, I wasn't faulting you for not being a mechanical engineer. I really was trying to show that the scope (aka budget) of the project you suggest is larger than you may think. At an extreme bare minimum, a few hundred dollars may get you the parts and raw materials... but it will be at least a couple of weeks of work (probably months) and trial and error before you get a working chair. And even with a cheap engineer's salary, that's in the thousands.

The devil is in the details, and initial design concepts always turn out to be harder than they seem at first.

Dave

I completely agree on your statement that the initial design concept always turn out to be harded then they seem at first.

Maybe instead of building it Maybe someone could just design it and I can try and build it. The thing I don't know is what motor to buy what gears to buy how to hook them all up to the motor and how to add the air system to raise and lower it. If someone has had experience or knows of a company that could do this maybe you can point me to them. Also, two other things. If I were to search for a company to try and do this for me what would I look for? What are these companies called? Would it be One-of contract manufacturing? I don't think so because that didn't work. and... Is there another newsgroup that might have people who can do this?

Like I mentioned I plan on having this chair for a long time so even if it takes a year to make it will still be worth it. Oh, if you are thinking about getting one of these I highly reccomend them. They are great. I have a premeier PH2026 $3000.00 but awsome except for the seat area and a few other minor problems. Thanks for all of your help. Russ

Most engineering constancy firms that design machinery could handle the design, but for a one of the cost would be prohibitive.

If you wanted to build it yourself this, would constrain the design to what you could make...... what workshop facilities have you got ?

From your initial description, you would need the firm to rework the chair design. They would be producing: drawings of all parts to be manufactured, a list of all other parts required with sources, and assembly instructions.

A project like this would take *at least* 120 hours, possibly charged at (pounds ) 60 per hour. I would at minimum use a first budget figure of £ 7500 for design.

It's the sort of job a student on a mechanical engineering course might take on as a final year project.

If you live within 10 miles of Guildford ( England ) I'd be happy to come and give you a quote for the job... :-)

"Russ" wrote in news:1129290805.303456.6360 @g43g2000cwa.googlegroups.com:

I've spent my career designing and building one offs. Actually we usually make 3/4 offs, not quite what you could call finished, but functional. I'd probably call a true one off a production run quantity. No one who has not actually done this sort of work ever believes how many hours are actually required. If you have to pay all the true costs, it will be $10k minimum. This if, and only if, you find a person or team with exactly the right skill and experience set. If not, it will be some multiple of $10k. The appropriate candidates for the job are either experienced mechanical fabricators (we call them Development Technicians here) or machinists with enough engineering to spec the drive components, a mechanical engineer with enough machine and fabrication skills to put it together, or a team of an engineer and builder who are used to working together. If the engineer has to produce a full set of construction drawings to give to the builder, the cost goes up.

A place to start looking is small job shops, although even in small shops nowadays machinists are being replaced by machine operators who want cad prints to feed into their tool routing software. Some of the shops will have a machinist who can do it, or know a ME who can design it for you.

Well, I want to thank everyone for the feedback. Jonathan I am a little to far from you to make the drive worthwhile. I am am California, USA. I guess I will start to try and do it myself. But if anyone knows of a particular shop or person in the USA who might be able to do this for a smaller fee please let me know. Even if someone finds this post in five years I will still probably be looking to get this done.

Thank you Russ

Dear Russ:

Start with a lawn chair. After a person in the act of sitting destroys any affordable mechanism, you can rest your idea cheaply.

David A. Smith