# Thread: Need expert guidance on rookie DIY build.

1. Hey guys, this is my first post so firstly I would like to say how happy I am at stumbling across such a well put together forum.

I am an absolute rookie in the field of cnc machining. However I have a big appetite for learning new things, so I will try doing as much of my own research as possible in between reading of your replies.

Basically I have a scenario where I would need to build my own cnc milling machine with selective requirements.

These are the requirements of the machined product:

- The slot will be 12mm diameter, with varying lengths.
- The material will be 5mm thick mild steel with a varying O.D. of 48mm to 114mm CHS.
- The length of material will be in the range of 1400mm to 3000mm.

The requirements of the machine so far will be:

- able to cut 5mm thick mild steel
- able to rotate along A axis of 0-359? degrees.
- able to work on material diameters of 48 OD chs to 114 OD chs
- able to work on material lengths of 1000mm to 3000mm.
- 3 axis (X,Z,A) (note: I will not need Y axis as I plan to keep the cutting tool centralised above the CHS at all times and let the X axis and rotational A axis do all the movement. the Z axis is simply for varying material diameters and for the cutting depth.)
- Would need to be cost effective.
- would need to be reliable. (the intention is to machine hundreds of these parts so reliability is a major factor)
- and finally, accuracy could be +/- 1mm.

I hope I have supplied enough information for the time being.

I look forward to, and appreciate any replies on this matter.

Steeki.

2. Interesting requirements. Any chance of explaining the purpose of these parts, especially given the low accuracy requirement.

1. Is the slot axial or radial to the CHS, or continuous in both e.g a spiral?
2. You say the slot is 12mm dia. Do you really mean width? The sides of the slot are perpendicular and the slot is centred axially on the workpiece's rotational axis.
3. Is this a one or two man operation? 3m of 114 x 5mm CHS weighs 23kg and is bulky.
4. How close to the end of the material does the slot have to be machined?

Given the length of the parts I would consider buying an off-the-shelf mill with required rigidity and throat capacity then building a custom material transport. I'd envisage a series of v-rollered supports for the bulk of the workpiece, some form of hollow hydraulic chuck to clamp/rotate the workpiece, fixed to the table of the mill for fine X movement and a feeder mechanism to give the bulk/rapid X movement.
Last edited by irving2008; 07-10-2014 at 05:34 AM.

3. You would need something like this :

Last edited by Boyan Silyavski; 07-10-2014 at 07:48 AM.

4. Originally Posted by irving2008
Interesting requirements. Any chance of explaining the purpose of these parts, especially given the low accuracy requirement.

1. Is the slot axial or radial to the CHS, or continuous in both e.g a spiral?
2. You say the slot is 12mm dia. Do you really mean width? The sides of the slot are perpendicular and the slot is centred axially on the workpiece's rotational axis.
3. Is this a one or two man operation? 3m of 114 x 5mm CHS weighs 23kg and is bulky.
4. How close to the end of the material does the slot have to be machined?

Given the length of the parts I would consider buying an off-the-shelf mill with required rigidity and throat capacity then building a custom material transport. I'd envisage a series of v-rollered supports for the bulk of the workpiece, some form of hollow hydraulic chuck to clamp/rotate the workpiece, fixed to the table of the mill for fine X movement and a feeder mechanism to give the bulk/rapid X movement.
Firstly, cheers for taking the time to reply mate. Appreciate it.

As for the product, it is something I prefer to keep as tight-lipped about as possible. But the slot will be of spiral shape (or helical?). It will cover no less than 90 degrees of the work piece and will be mirrored on the opposite side.

Yes apologies, width would be the right term. (I think I said diameter because currently I have to drill two 12mm holes and link them up by using a cutting disc.)

It is a one OR two man operation, of course depending on the size of the material needing slotted.

I have decided I will be using a 12mm slot drill so the start of the slot will always be 9mm away from the edge of the material, regardless of length or diameter. (15mm to the centre of the first cut)

I am on a really tight budget which is why I have listed my requirements to build a DIY machine solely for this purpose.

I am a fabricator by trade, so any structures would be easily rattled together. Its more the motors, electrics etc etc that pickle my head.

Steeki.

5. No problem, I like an intellectual challenge :)

How long are these slots? I just a little concerned how you'd move 3m of tubing under cutter and still have rigidity and repeatability since you can't necessarily take a 5mm deep cut, it'll need several passes.

6. Would a pipe threading machine convert ? extend stroke length, mount Z above, control rotation.

or this ?
http://www.jgsfab.com/tubepro.html
Last edited by EddyCurrent; 08-10-2014 at 08:11 AM.

7. Do you want to cut thru slots in tube or pocket slots for say Key ways etc.? . . . . This will make a huge difference to how the machine needs building regards strength.
If just thru slots then plasma is the simple way just like the link eddy provided if it's the latter then something similiar would work but would need Major strength and clamping at the cutting head.

8. Originally Posted by silyavski
You would need something like this :

If I had the money, this would be my machine alright.

Originally Posted by irving2008
No problem, I like an intellectual challenge :)

How long are these slots? I just a little concerned how you'd move 3m of tubing under cutter and still have rigidity and repeatability since you can't necessarily take a 5mm deep cut, it'll need several passes.
The slot will be a maximum of 300mm from the end of the tube and no more. so that is the basic cutting area.

Originally Posted by EddyCurrent
Would a pipe threading machine convert ? extend stroke length, mount Z above, control rotation.

or this ?
http://www.jgsfab.com/tubepro.html
Thats a brilliant job that. would be exactly what im looking for, minus the engraving tool. Although The chuck looks a bit small for my application.

On this note, what type of chuck is this? One with a through bore hole and clamps around the workpiece? This would be the first part of my jigsaw.

Originally Posted by JAZZCNC
Do you want to cut thru slots in tube or pocket slots for say Key ways etc.? . . . . This will make a huge difference to how the machine needs building regards strength.
If just thru slots then plasma is the simple way just like the link eddy provided if it's the latter then something similiar would work but would need Major strength and clamping at the cutting head.
its thru slots mate. Ive decided to use a 12mm slot drill to mill these slots out. Im guessing here, but maybe it would be cheaper to put together than plasma? Also running cost maybe cheaper? All I need is my machine set to a constant speed and feed rate as the material will never change, nor will the thickness.

I will try and draw something up to explain it better. Im sure we could all understand a few drawings

9. Apologies for the very basic drawing using MS Paint. But it should show what I have in mind regarding the machine, and what is required for the product.

10. Could I use the likes of a handheld mini drill as my cutting tool?

Page 1 of 2 12 Last

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•