[amartin2]

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[amartin2]

Hello everyone! This will be my first post to the forum =)

I recently purchased a G0704 and was in the process of buying a set of tool holders. I had read this great Guerrilla guide to CNC machining, mold making, and resin casting and after researching tool holding for a while, I wanted to ask you about the accuracy of the G0704. As a hobby, I work on robotics and I would like to do very very tiny cnc models similar to this image from the website:



Will I be able to get similar results as the image above if I buy the following tooling, or is it a waste of money to buy the higher-end tooling because the G0704 isn’t that accurate to being with?

R8 ER16 Lyndex – runout = 0.0001”
Rego-Fix Ultra Precision ER Collets - runout = ≤ 0.0002"

[Fastest1]

Welcome to the Zone!

Is the G0704 cnc'd? If so those parts would be possible. You could have done those on a Sherline too.

Btw most hobbyists cant afford or understand how to use a tool that would measure anything to .0001-.0002. IIRC a human hair is .001-.002 (so we are cutting that into 1/10ths?, for what?).

Your robotics projects will be achievable with almost any cnc hobby mill once the full process is understood. The G0704 is an excellent hobby mill on which improvements and or modifications are well documented and information is abundant. The better the tooling, set up and tool path generation, the better the results. There will be a learning curve, stick with it.

[amartin2]

Thanks for the kind response Fastest! The mill will eventually be turned into a CNC mill, but I wanted to make sure I understood the 'feel' of doing manually first so I wouldn't break as many bits or hurt the machine. Lucky I have experience with both 3D modeling, and tools paths for 3D printing that should prove useful for CNC milling. What is the most popular software for generating the tool paths? I've heard Mach 3 being mentioned quite a bit.

[Dylwad]

Mach3 only interprets the toolpaths and controls the machine, you'll need a CAM package to turn models into toolpaths, and the sky is the limit on cost and features there.

Sent from tapatalk

[Fastest1]

I use CamBam and BobCad. There are
plenty of others. Look around and see what others are using and what you want to pay (if anything).

Additive manufacturing is much easier on tools ;-)

I have both manual and CNC machines and am a hobbyist at the most. Though I read about how important the "feel" of machining is to be a good machinist, I am not sure I believe it. They are 2 different animals entirely. Sound is an illusion and higher speeds don't necessarily produce better finishes. Sounds simple, huh?

[691175002]

A g0704 spindle will probably have 0.005"+ runout at the tool tip regardless of how much you spend on collets and the RPM will be painfully slow. The spindle really was not designed for small endmills.

That style of work isn't really suited to a g0704 but won't be a problem as long as you are cutting soft materials with proper feedrates.

I would probably recommend a sherline if your work was limited to resin casting in small moulds. It will work out of the box and there is a company backing it.

[amyers]

A g0704 spindle will probably have 0.005"+ runout at the tool tip regardless of how much you spend on collets and the RPM will be painfully slow. The spindle really was not designed for small endmills.

what are you talking about, the runout on my g0704 spindle is only about .0006, stock, i think you have a decimal point off.

[691175002]

Runout gets progressively worse as you move away from the spindle face. If you stack an ER collet holder you will probably be 3-4" down so the runout will be pretty bad regardless of how good the collets are.

Now that I think about it though, just a 1/8" shank endmill sticking half an inch out will probably be better than one thou so you are right. I definitely wouldn't put an ER holder in the middle though.

RPM/vibration and backlash might still cause trouble with the genuinely small endmills though. I find that backlash comp tends to snap small endmills.

[amartin2]

Thanks for the advice, I will most likely end up getting some quality R8 collets.

I find it a bit confusing that TIR doesn't usually have an indication if it's inches or milimiters. I guess the most common default is always inches??

I will probably be milling softer materials like milling wax, RenShape 460, plastics, or aluminum so which shouldn't be too tough on the machine.

[SCzEngrgGroup]

A g0704 spindle will probably have 0.005"+ runout at the tool tip regardless of how much you spend on collets and the RPM will be painfully slow. The spindle really was not designed for small endmills.

Methinks you have a somewhat jaundiced view of these machines. I've never measured one of these machines that was anywhere near that bad, and never even heard of one that bad, and if I did I'd demand a replacement, even on an X2. If it were so, even 1/2" endmills would be nearly unusable, as at typical chiploads they'd barely be cutting on half of each rev, and exceeding allowable chipload on the other half. Plus, none of us would be able to maintain anything close to the tolerances we do without "fudging" our tool diameters, which I've NEVER had to do.

And, while runout can certainly *change* as you get further from the spindle, it is by no means certain it will *always* increase. It is entirely possible to have greater runout near the spindle nose, and much less runout further away from the spindle nose. It depends entirely on the root cause of the runout. It is also quite possible to reduce the runout of both the spindle, and the toolholders, by spending some time carefully fine-tuning them. Look at the thread by user Hirudin on the Novakon forum, who has done this to great effect, and in a very reasonable period of time. Overkill in my book, but we all find amusement in different places.

Similarly, the ER chucks and collets I've measured (all E-Bay Chinese bits), and others, have been generally pretty good - a few tenths runout. I use ER chucks almost exclusively, with a length of 3-4", and often go as small as 1/16" endmills with no problems at all. With 0.005" runout on a 1/16" tool with a 0.0004" nominal chipload, I'd be breaking tools left and right.

Regards,
Ray L.