Tiny CNC router

[j45on]

I think it will end up being MDF depends what I can get locally tomorrow
This is what i wanted to use



15mm thick with 11 layers we had some at work for transit flatbeds very strong
this is all I have left after making shelfs and a paper towel holder



Isn't MDF a bit of a pain to screw into ?

[dsquire]

j45on

It can be a problem putting screws into if not done properly. You should always predrill for screws before putting them in. Also, you should stay further away from the edge than in plywood. It is best not to put screws into the edges as it tends to split, especially if not predrilled. When using screws the worst thing you can do is to over tighten them and strip the threads out. Sometimes it is wise to use threaded inserts instead of wood screws especially if it must be adjusted or taken apart. 

Cheers 

Don

[HS93]

screwfix do MDF screws

Peter

[raynerd]

Amazing work so far, really impressed. Are you still happy with the motors and drivers you purchased on ebay??

I recently used MDF screws and they were excellent - much better then standard screws and I won`t be screwing into MDF again without using them.

Chris

[j45on]

Chris I am happy with the motors and controller for this machine but I have to keep the motor speed down or they make random thumps  missed steps ?
I did see a video on how to confirm missed steps in mach3 but I cant find it now 
For a larger machine needing more speed and power it may not be a good choice I think you might run into the problems mentioned previously but I'm no expert 
The motors are also very noisy when idle not quiet like the stepper on my rotary table
Here is a video of the noise

&list=UL

Can any one explain in simple terms what "decay mode settings" are for 
I am running 75% current and 1/8 microstep if that helps

[John Swift]

Hi Jason ,

its good to see your making progress

I've found a tutorial at stepperworld tha may help you understand the current decay setting

I would of expected 25% or 50% to be a good compromise ??

http://www.stepperworld.com/Tutorials/pgMicrostepping.htm

reference made to Allegro  in tutorial ,

   A3979 data   http://www.allegromicro.com/en/Products/Part_Numbers/3979/3979.pdf
   

 John

[j45on]

Cheers John  
I will have a read of that once I have washed the mdf dust out of nearly every orifice I have  

I failed to find any good ply today so 18mm MDF it is (this thing is not looking so tiny anymore   )



I am planning to cut grooves into the front,back and base pieces tomorrow( as shown bottom right in my plan)
so that with a bit of luck I can mainly glue it together and use less screws and prevent splitting, well thats the plan anyway  




Does anybody think this should belong in the project logs section ?

[John Stevenson]

It's not a log, it's MDF................

John S.

[spuddevans]

It's not a log, it's MDF................

John S.

But isnt MDF just finely shredded log?   


Tim

[j45on]

For those that asked about chinese laser cutters
I found the web pages where people documented their experiences with chinese laser cutters

http://www.imajeenyus.com/workshop/20090506_laser_cutter/index.shtml

http://www.andyslater.com/laser-cutting/

http://www.stephenhobley.com/blog/2011/04/11/buying-a-laser-cutter-from-china-part-one/

[Bluechip]

Hi Jason

Just had a very quick look at the links ... would this thing cut metal? ie something like .010" - .012" brass sheet?

Reason I ask is connected with something a mate and I were discussing last night, photo etched brass stuff. Like model railway wagons etc.



Dave BC

[j45on]

This guy has built a laser that cuts metal http://nilno.com/cgi-bin/index.cgi
But it will not cut brass   

quote from his FAQ page

"Can I cut brass?
No. I cant either. The industry would love to cut brass and they aint figured it out either. I gather it's a problem due to the heat transmission of brass and copper. It spreads out its heat over the area of the cut too effectively. If you cant concentrate the heat on a particular area, the metal doesn't get obliterated. Steel is a lovely and cooperative metal."

[Bluechip]

Thanks Jason

It was just a thought  ... and will forever remain so it seems ..



Dave BC

[John Stevenson]

Industry can cut brass with a laser, I have a stack of 3mm thick disks here that have been laser cut.
just how much power was needed I don't know as the laser is quite a big one, about 3.5 to 4 Kw but the point is it can be done.
Plasma will cut brass with no problems, even those cheap Cut40 machines.

Polly models are cutting the brass cab parts out for the poly loco's with a Pacer router.

John S.

[j45on]

What we need is a DIY water jet 

My apologies dave a bit of googling proves that brass can be laser cut 

[j45on]

I finished routing the base and sides today and it all fits together lovely  



My longer rails also turned up  

I'm thinking about turning up some large bed bolts to hold it together rather than glue and screws
or I maybe just buy some  

EDIT at £4.22 for a bag of 50 I dont think I will be making any

[HS93]

Are you going to Glue and screw it together? if so what are the bed /cabnet bolts for ?

Peter

[j45on]

Are you going to Glue and screw it together? if so what are the bed /cabnet bolts for ?

Peter

I was going to screw and glue but I may need to disassemble at some point so I'm going to use the bed bolts/cross dowels  http://www.screwfix.com/p/cross-dowel-m6-x-20mm-pack-of-50/22009
and these wide head bolts http://www.screwfix.com/p/joint-connector-bolts-m6-x-45-bzp-pack-of-50/64094

[HS93]

I would put some screws in as well  i get them from screw fix a big box 500  cheap they will stop any slip that you could get with the bed bolts

http://www.screwfix.com/p/mdf-tite-screws-3-9-x-40mm-pack-of-200/40376

peter

[j45on]

I'm hoping I wont need screws Peter

But I have some space left between the bolts incase I need to

Still have to bolt the base to the walls that can wait until tomorrow now

[Bluechip]

What we need is a DIY water jet 

My apologies dave a bit of googling proves that brass can be laser cut 

Hi Jason

Only just spotted this

No problem. It was only part of a fairly casual conversation. My mate Norm. does strange things with Railway Dioramas etc. He makes some rolling stock etc. from these (wr) etched bits of brass but no-one makes the obscure stuff he wants. ( Why doesn't that surprise me ).

As he knows I have occasionally etched PCB's, he asked if the same stuff would etch brass. 'Dunno, it does copper OK'.

I then said if even it will (?) it would take forever to do .012" brass, 'cos the PCB copper is nowhere near that thick AFAIK.

Hence to end of conversation, in which I had virtually no interest, I suggested CNC laser.

At which point I confessed to knowing somewhat less than zero about Laser cutting, CNC or otherwise.

Left it with him, then just asked as I noticed your project, which I'm enjoying quite a bit. 

Onward and Upward ..

Dave BC







 

[John Swift]

 Hi Jason ,

it's looking good ,now I know what to build as a first machine  

are you fitting your  laser to this one or a router?

can't wait for the video

I like the way the MDF parts fasten together  , all the parts being positively located

I must remember the threaded metal dowels for my projects  

 John

[John Stevenson]

Dave, just read thru an article that was in MEW about metal etching brass and they reckon 75 minutes to do a sheet of 10 thou brass, good article by a bloke called John Purvis, far better than the workshop practice no 36 Photo Etching.

John S.

[Bluechip]

John S.

Cheers, I'll point him in that direction  

No great desire to get involved really. Too many wheels on railway stuff.

Two is the ideal number. Any more is sheer exhibitionism, a gross waste of precious resource and should be expressly forbidden.

( might make an exception for Brewery Trucks)  

Dave BC

EDIT .. Owd on a bit .. current issue or what ???

[John Swift]

Hi Dave ,

while we are waiting for John to tell us what issue of MEW we need to read

have a look at this :--

http://steampunkworkshop.com/electroetch.shtml

 John