Grizzly g0704 cnc conversion

[aonemarine]

Well I got my G0704 mill today and the steppers and drivers. Im waiting on a conversion kit from arizona video on you tube to finish the pkg. I made a couple of passes with the mill today and can tell right away im for a learning cure. This mill is no where near as ridgid as my bridgeport. Im hoping that after getting to know it a little better, and getting the right speeds and feeds will improve upon the finish, time will tell..
any one play with one of these? I could use some honest insight...

 

[TimTaylor]

Hi,

I have a G0704 that is converted to CNC- had it about a year and it is working well for me. Mostly I machine aluminum and less frequently brass, primarily for making custom fixturing for laser measurement applications.

The biggest limitation is that these machines only have a 1 hp motor and you need to take that into account when calculating the chip load. Machinery handbook has tables for doing that, and there are also some decent feed & speed calculators for the PC around that calculate the hp requirement. I try not to exceed 90% and that seems to work well for me.

 

[aonemarine]

Good to hear Tim. So far its not the hp that im finding limiting. In fact im loving the variable speed motor. But the finishes im seeing on the edge of the part isnt what I am used to. Im sure in time i can compensate. Maybe im just looking for a quick soulution to issues i can see right now before the conversion...Like .010 lash in the screws.... I didnt expect a perfect machine when i purchased it, but all in all it aint half bad for the money. Just need to work out the quirks....

 

[Tin Falcon]

While waiting for the mounting kit you may wan to dismantle clean out the slime and chips debur the sharp edges and maybe even make new gibs.
on my mini had to make new gibs . the gibs would gust not adjust. It was either too tight or too loose depending on position of the table.

As far as feed and speed that should be a calculated constant for any machine. But you will likely have to back off on the depth of cut from what you are used to on the Bridgeport.
Tin

 

[TimTaylor]

Good to hear Tim. So far its not the hp that im finding limiting. In fact im loving the variable speed motor. But the finishes im seeing on the edge of the part isnt what I am used to. Im sure in time i can compensate. Maybe im just looking for a quick soulution to issues i can see right now before the conversion...Like .010 lash in the screws.... I didnt expect a perfect machine when i purchased it, but all in all it aint half bad for the money. Just need to work out the quirks....

Yeah, it could be backlash, or as Tin suggested there could be some crud causing problems as well. A good cleanup and adjusting the gibs may help.

Were you using conventional or climb milling? With climb milling the cutting forces pull the material in the direction of feed and any significant backlash can cause problems with the cut.

Due to time constraints, I had mine converted commercially, so never ran it with the original screws. With the ball screws and slightly oversize balls in the nuts, it has less than 0.001" backlash.

Tin - for speed I use the formula 4 x SFPM / cutter dia. For the finish cut I find that taking a thin cut of 0.003 or so and increasing the speed by 15-20% depending on the material gives a better finish.

I agree that the best way to reduce the power requirements is to reduce the depth of cut. That said, feed rate, depth of cut and the number of flutes all affect the chip load and required HP. Within reason you can play one off against the other - i.e. be able to make a deeper cut by reducing the feed rate.

 

[aonemarine]

Once the ball screw kits get here I will be tearing the whole machine down and going thru it which is probably a good idea for anyone who buys one of these machines. Ill have to go thru some other threads about scrapeing as well so I can really clean up some of the machining done on the ways. I plan on at a later date up grading the spindle motor and bearings to get some more hp and rpms in the 7k range. I plan on using this mill for making small patterns and molds for my casting work. Im waiting on a new set of collets as well, I checked the run out on my 3/8" collet on this machine and im seeing .001" run out so im sure that doesnt help.
AARGH!! come on ball screws! I want to get this thing up and running asap!!

 

[TimTaylor]

Unfortunately 0.001" spindle runout isn't all that uncommon in these machines. Changing from the stock tapered roller bearings to angular contact bearings will address both the maximum spindle speed limitation and runout issues.

Hoss has a pretty good collection of mods for this mill on his G0704.com site. Most of them he has also documented in threads on cnczone as well.

Eventually I plan on some upgrades, including the angular contact spindle bearings and replacing the existing motor & speed controller with a 1.5hp 3 phase motor, VFD and cogged belt in lieu of the existing gears, but will probably wait until the existing motor gives out.

If you want really high speed, consider building a bracket to mount a small high speed spindle (i.e. commercial laminate trimmer) to the existing spindle - lots easier & cheaper than mods to the original head.

 

[aonemarine]

Ok the new collets arrived and I re checked the run out, its just under .0005" Much better! So I decided to throw a whopping 1" dia 4 flt end mill at it and see what it would do. Width of cut 1.5" DOC .010" (do I have the right or is it the other way around?) 1000 rpm and 5 ipm (my best guess when cranking) and it got a beautiful finish. I have also fed the machine some brass, 1018 steel, 4130, 303 ss, and its chewing right thru it all.
Im pretty happy with the machine so far. Im going to start checking it for accuracy across the table next and see what I get. My ball screws should be completed and shipping by the end of the week. I see some real fun in the near future!

 

[aonemarine]

sweet!!

 

[RonGinger]

very nice. I just came to sit down after moving my new G0704 mill into the shop. Its still covered in the "cosmogoo", or is it dragon fat?

So far I am very happy, it all looks good and the motor sounds fine. I have not tried to crank the tables much since all teh goo is still on, but after a rest for a while I will be back in the shop to clean it up.

This is going to be a manual mill, along side my Jet CNC conversion. But it does look like a fine machine for a CNC conversion. I just bought a glass sale DRo off ebay for $385, including shipping. Seems to good to be true, hope its OK.

 

[TimTaylor]

Its still covered in the "cosmogoo", or is it dragon fat?

Ron - I always thought it was Dragon SNOT.....:hDe:

aonemarine - looking good! It's a very capable machine - think you'll have fun with it.....

My new lathe arrived Friday and I spent several hours Saturday & Sunday building a good stand for it and getting it mounted, leveled, etc. Tonight I need to take off the 4-way tool post and figure out what I need to do to convert to 100-AXA QC setup so I can get the parts ordered - never a dull moment......

 

[aonemarine]

I all ways thought it was wok grease LOL

 

[TimTaylor]

Any progress on your conversion project?

My x-axis stepper started acting up over the weekend - fortunately I had just finished the machining work for the QCTP conversion for the new lathe, so was able to complete that project.

I was able to isolate the problem to the motor - it's acting like there's an intermittent connection. I checked the cable, connectors and splices and everything was good, so I expect it's something internal to the motor -ordered a new stepper to replace it. When it gets here I'll probably tear into the old one to see what the issue is.

While I was at it I also ordered an Ethernet Smooth-Stepper interface card - been thinking about upgrading to that for a while, so decided to get one coming so I can start playing with it.

Tim

 

[aonemarine]

TIM, I've been waiting on the guy to finish up the ball screw kit for me. I just got a pay pal invoice yesterday and he was supposed to ship today. The guy must work like I do...slowly. lol
Maybe ill see it by the weekend...

 

[aonemarine]

Lookey lookey, kit arrived in the mail today. Im very happy with the work he put into making it, worth the wait...

 

[TimTaylor]

Very nice looking hardware! Bet I can guess what you'll be up to this weekend........

 

[aonemarine]

Very nice looking hardware! Bet I can guess what you'll be up to this weekend........

Ha Ha nope... Ill be stripping paint off my model a, well some paint, mostly rust

 

[aonemarine]

well 9.5 months later and I finally got a round tuit. got the cnc mill up and running over the weekend. First run video..
http://youtu.be/H70V09xrfKI?list=UUSrlSdQ3dLlHlahmmmYbb2A

 

[Wizard69]

well 9.5 months later and I finally got a round tuit. got the cnc mill up and running over the weekend. First run video..

Nice video, thanks for the update! As to that 9.5 months, don't you just hate it when life gets in the way. I have many projects that have dragged on far to long now, it is always something from cash flow, to too many feet of snow in the driveway, to house repairs to whatever.

In any event update the thread from time to time with info and posts showing what you have made with the machine.

 

[tms6401]

Very interesting ... I have the same mill only in a different colour and part number.

CNC would be interesting.

Cheers

Tom