Introduction

**eltel** · 08-09-2009

Hi, Just a quick hello from a new member. I am attempting to design/build a smallish cnc gantry machine to make prototype double sided pcb's. The intention is to use aluminium profile for base and as much mechanical bits as possible, trapezodial shaft for drives, nema23 steppers with own intelligent controller ( possibly propepeller or FPGA based ) communicating with pc over usb. Looking at 4 motor design ( 2*x, 1*y,1*z). Possibly making own delrin drive nuts ( stupid prices to buy). Got excellent quotes from china for pillow blocks etc roughly 1/2 uk price, but in dollars. So should be okay for freight/duty. Having trouble getting low cost tap for Left hand thread. ( X axis one=rh and one=lh so torque is balanced.) Shafts are 20mm for x and y, trapezodial 16mm. Z to be decided, it may be cheaper/easier to stick with 20/16 but who knows. I hope to be able to get the design firmed up over the next few weeks, any input greatfully accepted. My background is mostly electronics, but I started life as an apprentice plater in a steel works making overhead cranes. Did OND in engineering, then bsc in electronics, and have got PGC in electronics from bolton univ. Studying to get the diploma and then (perhaps) Masters. My workshop contains compressor, MIg welder, plasma cutter, pillar drill, burgess bandsaw, trolley jacks, stands etc. I also have access to my mates lathe. I maintain my cars and my daughters. Having spent hours searching the web for inspirtion I read a lot of very good posts here so I decided to join up.

**HiltonSteve** · 08-09-2009

Originally Posted by eltel

Having trouble getting low cost tap for Left hand thread. ( X axis one=rh and one=lh so torque is balanced.) Shafts are 20mm for x and y, trapezodial 16mm.

Welcome eltel....

I am sure John S had a discussion with somebody about making taps out of the M16 left hand trapazoidal thread .

When he see's this he may be able to shed some light on it, just depends what mood he is in...:whistling:

**irving2008** · 08-09-2009

Originally Posted by HiltonSteve

Welcome eltel....

I am sure John S had a discussion with somebody about making taps out of the M16 left hand trapazoidal thread .

When he see's this he may be able to shed some light on it, just depends what mood he is in...:whistling:

It was M10 not M16, but the principle holds

He suggested getting an extra length (200mm) of the trapezoidal, and flute it and he would get it cyanide hardened (for my brass nuts). However for Delrin nuts it wouldnt need to be hardened.

Basically fluting involves grinding some slots along the length (3 or 4) and then grinding/filing a taper (best done in the lathe on the first couple of cm.

Oh BTW, welcome ElTel

**Kn8** · 08-09-2009

Hello eltel, welcome. :wave:

**John S** · 08-09-2009

Originally Posted by HiltonSteve

Welcome eltel....

I am sure John S had a discussion with somebody about making taps out of the M16 left hand trapazoidal thread .

When he see's this he may be able to shed some light on it, just depends what mood he is in...:whistling:

piss off............