looking for a machinist....

[dennisdzh]

Hello,

I am looking for a machinist who can make some parts for me. I need to have a minature track made, but I don't have the skills nor time to make this myself, so I was hoping someone could help me out. I am of course willing to pay for your time.

I have attached a close up photo of the end of the track which measures: 145x6,3x3,5mm (Length x Height x Depth). I have also attached a technical drawing I made (not the best I might add, but it gives an indication of the measurements).

Please contact me at dennisdzh(at)gmail(dot)com if you can help me out.

Thank you for your time.


Sincerely,

Dennis

 

[Deanofid]

Dennis, you should tell where you live. At least the country, and the general area of your location. It will help you in getting some useful responses. What I mean is, you might want someone at least in the same country if this has to be shipped.

 

[steamer]

Hi Dennis,

Do me a favor and post an introduction in the welcome section. We all really want to know who our new members are. Thanks!

Dave

 

[Tin Falcon]

An intro would be good. And some more details. location material what is this used for . It this a hobby item.
IOs the photo of a part worn beyond use ? clear communication. I have heard of stories where someone brings in a part to be duplicated. Make like this and the part is reproduced in exact details including the wear marks that put it out of spec in the first place.
Tin

 

[Dan Rowe]

There are several things missing on the drawing the only height dimension is the outer dimension. The internal height at the bottom and the width and the height rectangular groves have to be measured. Also there is no material specification.

And as mentioned by the Mods an intro and a location are the normal requirements to start a conversation on this forum.

Dan

 

[dennisdzh]

Hey Guys,

sorry for the missing intro and the missing information - and thanks for reminding me.

Intro:
I am a 24yr old man from Denmark. I am currently studying, and have a few projects as hobbies on the side. I found this forum using google, and I was surprised to flip through some of the posts and see some really amazing work!, so I thought this would be the right place to get some help.

The material is: brass

the function of the track: to manually pull a sliding flat bar of steel through (I was told that brass and stell has very little friction, so these would be ideal for the purpose of this). The track is to be added to a robot I am currently working on.

Dann Rowe, yes you are right, some dimensions are missing, but I didn't know how to measure these exactly, so I have to make some trial & error attempts, to see what will fit.

Once again, thank you for taking the time to reply to this post.


All the best,

Dennis

 

[Tin Falcon]

, so I thought this would be the right place to get some help.

Well we will see. The primary focus here is folks building model engineering as a hobby . And folks sharing that knowledge and helping others build model engines.
So if someone wants to help you fine if not well that has to be ok also . good luck. If at some time you want to learn to machine your own parts you will likely get much more help that is more of what this forum is about.
Tin

 

[Mainer]

What are your dimension tolerances? Is there any chance the original part was manufactured to Imperial (inch) measurements? I ask because the width is within 0.002" of being 0.250" and the width of the center groove is close to 0.125". If tolerances permit, it would relatively simple to mill the center groove in a piece of 1/4" wide brass stock with a 1/8" (0.125") ball end mill, then mill the two side slots with a tiny Woodruff cutter.

What sort of loads will this be subject to? Could you make it out of Delrin (acetal) plastic? Acetal is very slippery and fairly strong, and it machines easily.

 

[dennisdzh]

Once again, thanks for writing me back! I truly appreciate you taking the time to help me out, because all of this is new to me.. so thank you all!

Mainer:
Sorry for the ignorance, but what is dimension tolerance?
The original part was made in The U.S., so the measurements were probably in inches, so it was probably made as you suggest with the 1/4" wide brass stock.

It will only be subject to very light loads. The only purpose of the track is to have a very thin and flat steel bar pulled through the track, and the hole in the bottom of the track (shown in the above photo and drawing) is only there to create room for the nylon string that will be pulling the flat steel bar.

I hope this makes sense.

regarding if it could be made out of other materials... I had thought about making it out of Teflon (with the purpose of reducing friction), and then give it a brass casing, but it seems to raise even bigger issues, so I kinda got stuck on the brass/steel combo. On second thoughts, I think it would be better to stick with the brass version, because I have to solder it to other pieces of brass that will increase the stability of the track.

Dennis

 

[ShedBoy]

Side note here. What is the robot for? Fighting? Maybe some pictures showing its location and needs will help?

Brock

 

[Tin Falcon]

A dimensional tolerance is aan allowance given that a particular dimension can be bigger + or smaller - than the given dimension.
A typical general machining dimension is usually +-.005 inches.
a piston -.0005 +.0000 a bore +.0005 -.0000 .

Precision measuring and tolerances are what has allowed and driven mass production and allowed for interchangeable parts.
Precision is expensive. so tolerances have to be right for the job . tolerances unnecessarily tight drive up production cost. Too loose and parts are useless and will not fit together.

A home model print may just give a dimension for the bore . the piston may say turn to fit cylinder. So in the home shop tolerances and actual dimensions are not as important as how thingsfit together and work .

Hope this nutshell explanation helps.
Tin

 

[mhh]

Hey Dennis where in DK are you located? I might be able to help.

 

[dennisdzh]

Tin Falcon...

Thank you very much for that comment. I just learned a lot!

The track doesn't have to be exactly those dimensions, although it would be best if the height doesn't change more than one milimeter.
The round milled section in the center can be smaller, also about 1 millimeter, as there only have to be room for the nylon string.



mhh....
I'm in Roskilde. I don't know if this forum allows any other communication than english, but you are very welcome to contact me at dennisdzh(at)gmail(dot)com, then I can also provide you my phone number.

Once again, thank you for the replies.

 

[mhh]

mhh....
I'm in Roskilde. I don't know if this forum allows any other communication than english, but you are very welcome to contact me at dennisdzh(at)gmail(dot)com, then I can also provide you my phone number.

Once again, thank you for the replies.

I'm currently in China so for some strange reason I cant get into my gmail account (Wonder why? ;D ) So I'll email you when I get back to Denmark. Just one question: what is the dimension on the groove?

 

[hax]

thank you for the tip!

BRGDS
Tom

 

[Dan Rowe]

Dennis,
How do you plan to attach the track to the robot frame? A simple solution might be to alter the design of the inner bottom surface. A standard milling cutter will leave a square bottom so flat head machine screws could be used in the string grove to attach the track.

If China blocks Gmail the PM system on the forum should work.

Dan

 

[dennisdzh]

mhh...
Okay sounds great. Just e-mail me whenever you have time. I'd really like to have a chat with you about this as soon as you can. regarding the groove, its dimensions are not exact, as it just have to fit with the flat steel bar that will be going back and forth inside of it. This also goes for the section where the nylon string is supposed to be.

Dan Rowe...
I plan to solder the track to other brass parts. There is a reason as to why I am doing this.. I don't want to get too much into details about this, but it has something to do with the other side of the attached brass parts. The surface has to be smooth there.

I really appreciate all the feedback I am getting here! Thank you so much! all of you! I promise I will post photos of the finished project.

Dennis