[Harv22]

Hi all,

I have read through a lot of build threads here at CNC Zone and on the net before starting by build, it seems only fitting that I contribute to this community as well. A shout out to a few of the ones that come to mind Russtuff, CNC Cookbook, MrBallistic31, and last but defintly not least Hoss. If you haven't read their build threads skip the garbage im going to share below and come into the light.

My mill has been CNC'ed with the stock screws for now. All three axis are direct drive with 570 in-oz stepper motors and KL-5060 drivers from automation direct. Power supply is actually two supplies connected in series If i remember correctly its equivalent to something like 36V @ 6A definitely a limiting factor but it was free.

I run rapids of ~60 IPM, and have ~0.006" of backlash in X and Y. These are NOT spectacular numbers and I could get a little better if i lapped the ways but hey its up and running.

Most of the build will be documented via pictures, if their is something you would like more detail on feel free to ask.

Took Delivery of my mill (7/9/2013)
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Electronics
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Stepper Motor Attachment
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First Part, Z Crank Cover
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[Harv22]

Here is a picture of my garage and computer station an enclosure is in the works.

Attachment 224244

Here are a few projects that I have completed on the mill.

Pacman bottle opener:
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Tool Organizer:
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Tractors:
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Which led to an auxiliary spindle of course . I bought a re-manufacture Bosh Colt from amazon and a collet kit from Precision bits. I am very happy with both.
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This worked well for the wood, but I immediately attempted to replicate what Hoss achieved here

G0704 Aux Spindle at 50 IPM - YouTube

I quickly discovered my mount was not even close to being rigid enough. I am in the process of re-making it.

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[Harv22]

After nearly a year of dragging chips into the house it was time to build an enclosure. My chip tray is loosely based off the print on Hoss project page here
Projects.

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I combined it with the shower curtain idea from CNC cookbook here Introducing Michael Hackney: Our New 3D Printing Guru - CNCCookbook CNC Blog CNCCookbook CNC Blog

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This is what i ended up with in CAD. During the build i realized I needed extra supports on the sides and that the whole thing wider in the Y axis by 6" to accommodate the travel mod when i go to ball screws.

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I don't have a table saw so i made a guide for the trusty skill saw.

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All the pieces were assembled with wood glue and an air stapler.

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I put silicon on all of the seams, it comes in both clear and white pictured tube is clear enclosure has white.

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I painted the wood with high gloss exterior paint and the top ring with white epoxy pait. We will see if it holds up when i add flood coolant.

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And fully assembled.

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and that my friends brings us up to date.

[hoss2006]

Nice work so far Harv! I'll mention the need for some bellows on there before someone else does.
Keep up the great info, never enough G0704 threads.
Hoss

[Harv22]

Thanks Hoss! I have the rubber to replace the covers I will get on that Today is an aluminum detox day for the house.

[Fastest1]

Lapping your ways would not help your backlash. It will make the table easier to move but that is about it. Without going to a double nutted ball screw, you most likely will hover around the amount of backlash you show now.
Do you run backlash comp?

[arizonavideo]

I'm still trying to understand the love for double nuts for hobby machines.

If the ball nut is already offset ground or as they call it lead shift ground then is is for all practical purposes two nuts with the difference being the number of ball that will see load in either direction and the ability to adjust the preload. If you double nut a offset ground nut you are effectively bypassing half of the balls in each nut. You could remove them and the unit would turn more freely without the useless balls.

A proper double nut system will use standard ground nut tracks not offset like the C7 China screws.

This is a link dispelling the double nut requirement a fair bit.

Ball-screw basics: Debunking the myths | Mechanical Drives content from Machine Design

Now if people are still getting backlash with offset ground nuts they should add over size balls in at lease half of the nut tracks not go to double nuts.

I like the back lash nut adjustment system much better on the 704 than the Rf-45 setup at lease on the X and Y. I would think after the screws break in you could adjust them to get down to .002" or so. The Z is a problem as it has no adjustment.

Harv: how did you connect the couplers to the Z? I take it you have a lathe and turned the couplers to fit?

[Harv22]

@Faster1: Agreed, lapping will not have a direct effect on backlash. That said I feel if i had more consistent drag on the tables i could tighten down the adjustment screws more and thus reduce the backlash only way to truly find out is to do it.

I also have a hard time believing that a single nut ball screw will not not reduce the backlash significantly. I mean the advertised spec on the C7 ball screws from Automation Technologies (had it wrong in the earlier post) is 0.0006" hopefully the stage and bearings would not magnify this by 10x.

New Ballscrew Kit G0704101015 for Hoss G0704/ BF20 CNC Conversion | Automation Technology Inc

@arizonavideo99: I do have a HF 7x10 lathe that i used to make the stand offs and drill and tap the couplers. That said I don't know that a lathe is required for what i did if you are creative with the mill and have a V block to put in the vice.

Here is a pic of when I was test fitting the Z coupler. I ended up removing one jam screw in the end without issue.

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[SCzEngrgGroup]

I'm still trying to understand the love for double nuts for hobby machines.

If the ball nut is already offset ground or as they call it lead shift ground then is is for all practical purposes two nuts with the difference being the number of ball that will see load in either direction and the ability to adjust the preload. If you double nut a offset ground nut you are effectively bypassing half of the balls in each nut. You could remove them and the unit would turn more freely without the useless balls.

A proper double nut system will use standard ground nut tracks not offset like the C7 China screws.

This is a link dispelling the double nut requirement a fair bit.

Ball-screw basics: Debunking the myths | Mechanical Drives content from Machine Design

Now if people are still getting backlash with offset ground nuts they should add over size balls in at lease half of the nut tracks not go to double nuts.

I like the back lash nut adjustment system much better on the 704 than the Rf-45 setup at lease on the X and Y. I would think after the screws break in you could adjust them to get down to .002" or so. The Z is a problem as it has no adjustment.

Harv: how did you connect the couplers to the Z? I take it you have a lathe and turned the couplers to fit?

You are talking about *ground* nuts. Almost NONE of the screws or nuts being used here are ground, unless they're E-Bay finds. Virtually everyone here is using *rolled* screws and nuts, which do not have offset tracks because they are not made precisely enough to use that method. Hence, the need for double nuts to achieve zero backlash. Ground screws and nuts cost on the order of 3-5X as much as rolled ones.

Regards,
Ray L.

[dracozny]

You are talking about *ground* nuts. Almost NONE of the screws or nuts being used here are ground, unless they're E-Bay finds. Virtually everyone here is using *rolled* screws and nuts, which do not have offset tracks because they are not made precisely enough to use that method. Hence, the need for double nuts to achieve zero backlash. Ground screws and nuts cost on the order of 3-5X as much as rolled ones.

Regards,
Ray L.

the article covered rolled screws as well, china may use a poorer method of rolling but high accuracy is possible with some manufacturers.

[SCzEngrgGroup]

the article covered rolled screws as well, china may use a poorer method of rolling but high accuracy is possible with some manufacturers.

Many of the Chinese rolled screws are really not too bad. Some come very close to zero backlash. But even the high-end US-made ones are not truly zero backlash without double nuts. I used the best rolled screws on the market - Nook XPRs - when I converted my knee mill years ago, and even the $$$ XPR nuts were not zero backlash unless double-nutted.

And, it's incredibly difficult to achieve zero backlash with ball-select as and end-user, because you have access to only a very limited number of ball sizes. Manufacturers can get balls in a wide range of sizes.

Bottom line is, double nuts works very well, and are easy and cheap to make. It's still the best route to true zero backlash for the hobbyist, and most of the alleged downsides are unlikely to ever affect a hobby machine. You have to understand the concept of "good enough". Many of the things that affect industrial machines simply don't apply to hobby machines.

Regards,
Ray L.

[Harv22]

Started on a flood coolant system right after install the way covers per Hoss' orders

This was my initial attempt, i used the fittings and tubes shown in the drawing below. The drains are just random pluming fittings from homeDepot that i drilled holes into so coolant wouldn't sit in the bottom tray.

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Almost immediately I regretted necking down the return line to the flexible tube. The little filter in the tank was never intended as a long term solution to filtering but i realized I was so far away from what would be required that I started over. I didnt get as many pictures of the re-build as i would have liked because i was mostly making it up as i went.

Here is how the pump is currently mounted in the tank. What you see is actually just a small paint container with the fine filter material covering it (pantyhose).

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The rough filtration is just some metal window screening material from HomeDepot. Its held between the 5 gallon jug lid and a small pail that i cut the bottom out of.

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I replaced all of the smaller fittings on the return lines with with flexible hose that fit over the 3/4" PVC i already had in place.

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I have ran some initial test and everything seem promising, hopefully i will be able to do some actual machining this weekend to fully test it out.

[Harv22]

I took delivery the C7 ball screws from automation technologies today

New Ballscrew Kit G0704101015 for Hoss G0704/ BF20 CNC Conversion | Automation Technology Inc

Thought it would be interesting to show a before and after performance so this post is to serve as a record of what I was running with the stock screws.

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[Harv22]

Had a chance to play with the mill and flood system today.

I found out that if i was roughing out a LOT of material I could still plug the PVC section of the return lines. I will have to keep the area around the drains clear. I made some custom drain covers that have helped the issue as well. They are secured with a dab of JB weld so i can vacuum out the chips after they dry without loosing the covers.

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I also made a mount for the loc-line. Some of the bends are rough but i was happy with the results remembering they were completed with a vice and hammer .

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I also wanted to add so far i have seen no adverse effects of the coolant on mill (i.e no rust, no paint stripping). I mixed the Kool mist coolant per the instructions on the jug with water from the kitchen faucet. For clean up i blow off the table/vice/ways with the air compressor and walk away. If anything develops new develops i will let you know.

[Fastest1]

Ditch the covers. Use a much bigger diameter drain, 2-4" at least. Got a lathe? Turn one. You could even mill one and bolt it in from the bottom with a gasket. If know screen always seem to clog.

[Harv22]

I agree a bigger drain would be better, but if you go back at my first post for the enclosure you will see that I still have the original pan on the mill. Thus no room for such a large drain guess it is something i would do different if i started over.

[hoss2006]

You can fit a 1 1/4 drain in the stock pan if you don't mind it going thru to the inside, worked pretty well.
Hoss

[Harv22]

Finished off the auxiliary spindle mount today after work. Unfortunately I grabbed the wrong end mill while I was doing the counter bores on the clamp hence the cosmetic issues.

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While attaching the router i noticed that it has some "play" don't know if that is the right word it almost feels like it has to positions the shaft can go between. I will need to look into before making any cuts.

I also made an extender for the quill lock, as you can see its getting crowded on the left side of the mill.

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[DonKes]

Home depot has a nice answer to the drain problem. They have a 24x36x7.5 inch heavy plastic tub.

Plasgad Large Mixing Tub-887102A at The Home Depot

Don

[Titaniumboy]

Harv,

Very nice G0704 conversion you have going here. Are you still on the stock screws or have you already gone to ballscrews?

I also made a mount for the loc-line. Some of the bends are rough but i was happy with the results remembering they were completed with a vice and hammer .

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I also wanted to add so far i have seen no adverse effects of the coolant on mill (i.e no rust, no paint stripping). I mixed the Kool mist coolant per the instructions on the jug with water from the kitchen faucet. For clean up i blow off the table/vice/ways with the air compressor and walk away. If anything develops new develops i will let you know.

Nice job on the Loc-Line mount.

Where did you get the Loc-Line from? Does your Loc-Line have inner vinyl tubing? The reason I'm asking is that I have a new Novakon Torus CNC mill and my Loc-Line appears to be generic and has clear vinyl tubing on the inside.

I'll be interested on how the Kool Mist ends up working for you. Where did you source your Kool Mist from, and how many gallons did you have to buy?

Thanks for the help.

Titaniumboy