Author Topic: My New Mill  (Read 10139 times)

Offline 75Plus

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My New Mill
« on: January 16, 2011, 10:20:15 PM »
I recently took delivery of a new Grizzly G0704 mill/drill. Weiss (WMD20VL clone) Fit and finish looks good but I do have a problem with the drawbar setup. First the drawbar retainer cup starts to remove its self long before the collet is properly tightened. I would think that there would be a setscrew to prevent this but I can find no evidence of it. I called Grizzly Tech. service last Friday but the guys in the know were unavailable. Perhaps they will call with answers later this week. The next issue is where do I get a third hand? The instructions caution one to place a hand beneath the tool being removed to prevent it falling onto the table and possibly the floor. With one hand backholding the spindle while the other hand turns the drawbar the table will just have to fend for its self.

I know how the drawbar system is SUPPOSED to work but this system is a prime candidate for a power drawbar mod. In the meantime I am going with plan "B". I spent the afternoon making a spanner that fits the spline of the spindle. This will allow me to change tooling similar to way I do on my X-2. I can still use my combination spanner/mallet. I still must add a handle but the hard work is completed, making the spanner head. I have a posted a CAD sketch showing how I made it.

Still need to tram it so it will cut true. I will be back if I need help.

Joe

Offline Brass_Machine

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Re: My New Mill
« Reply #1 on: January 16, 2011, 10:33:50 PM »
Joe

Don't have the answer for you as I am not very familiar with that mill. However, I want to be. How about a photo review when you get yourself squared away?

Eric
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Offline Bogstandard

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Re: My New Mill
« Reply #2 on: January 17, 2011, 02:43:43 AM »
Joe,

Just a few things I did to get over my problems in this area.

I found that when I used to have a morse taper spindle, the tool wouldn't release until the drawbar was given a hefty wack, so there was time to put your hand underneath to catch the falling tool before you hit the drawbar. When I then went over to an R8 drawbar, which released the tool at the slightest whim when the drawbar was loosened, I soon learned to put a large rag under the tool to catch it as it fell. I only lost a couple of 100+ buck carbide tools by them bouncing them off the vice before I learned that trick.

The first thing I bought myself was a cheap ratchet ring spanner, one way to tighten, flip it over to slacken, plus if you forget to take it off after tightening, and start the machine, you will only get a ratchety sound rather than a nasty jam up.

I am lucky in that I have a spindle brake that locks things up when I want to remove the drawbar, if you don't have one, a search on the web will give you some ideas on how to fit a spindle lock to yours, that will leave your third hand free to do whatever you want with.


John
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Offline DavidA

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Re: My New Mill
« Reply #3 on: January 17, 2011, 08:15:10 AM »
On the Victoria,  Elliott and Cleveland mills I used at work we simply undid the drawbar nut about a turn,  then tapped the end of the drawbar with a nylon mallet whilst holding the chuck with the other hand.  It could only drop about half a millimeter anyway. Then you just unscrew the bar while holding the chuck.

Dave

Offline AdeV

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Re: My New Mill
« Reply #4 on: January 17, 2011, 11:22:46 AM »

The first thing I bought myself was a cheap ratchet ring spanner, one way to tighten, flip it over to slacken, plus if you forget to take it off after tightening, and start the machine, you will only get a ratchety sound rather than a nasty jam up.


Good thinking.... I've smashed one wristwatch, and got one bruised wrist, where I've let that happen. Fortunately for the machines, provided one is driving the spindle forwards, it will simply bash into your wrist (this is assuming the Bridgeport switch position), causing either great pain, or Death Of Wristwatch, the drawbar then undoes itself, dumping the tool & collet onto the workpiece - they usually bounce & hit the floor, thus damaging both tool & collet...

An expensive do.

I will definitely try out the ratchet spanner.
Cheers!
Ade.
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Location: Wallasey, Merseyside. A long way from anywhere.
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Offline Jonny

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Re: My New Mill
« Reply #5 on: January 17, 2011, 12:06:44 PM »
I just leave a spare 16/17mm open ended spanner close by, 1/4 rev tap it with hammer close by. MT3 can be a bitch at times.

First thing i did was make a spindle lock on similar Super Lux. This was a sprung plunger type locking in to any of the splines, still going well.

I will have another look at one of those 836 Bogs.


Offline 75Plus

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Re: My New Mill
« Reply #6 on: January 17, 2011, 04:55:27 PM »
Thanks for the suggestions. I am posting some pictures to help in understanding the problem. I did receive a call from the Grizzly tech and was told that the nose of the spindle should have two flats for a spanner to hold it. I believe that is the way the X-3 spindle is held. In any case I have no flats.

The theory of operation for this drawbar is that the retainer cup will supply a place for a 17mm spanner to backhold while you tighten or release the collet. It is designed so that continuing to turn the drawbar anti clockwise it will contact the top of the retainer thus forcing the collet loose and not requiring the mallet. Theories don't always work in real life. The fact that both the drawbar and the retainer cap have right hand threads and there is no positive lock to prevent the retainer from turning dooms this scheme to failure. Both the Grizzly tech and I agree that this machine is a PRIME candidate for a power drawbar. That may be an option for later consideration.

This is what is seen when the access cap is removed. The spline is approx. 1/2" below the top of the motor cover.




With the cover is removed this is what you see.



With the retainer cap removed you can see the, somewhat odd, drawbar. It has a 8mm square spigot for turning it. The supplied spanner is only 4 1/2" long which limits over torquing or promotes under torquing, take your pick.




Here is the spline I made the spanner to fit. I pretty well followed the sketch I posted previously.





Two views of the spanner I made. I still must weld the handle to the body.





This is how it will be used once I get a new drawbar made.



Once the project is complete I will be able to continue using this to secure and remove tooling.



Joe
« Last Edit: January 17, 2011, 05:02:42 PM by 75Plus »

Offline jiihoo

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Re: My New Mill
« Reply #7 on: January 18, 2011, 03:55:36 AM »
Hi,

I don't have a Grizzly but a similar small mill. Take a look at the spindle nose from below (looking up from the X-Y table). Look at the spindle nose right at the end where you insert your MT3 tools or MT3 collets. Do you see two flats there? If you do, then those are the two flats that the Grizzly tech probably referred to.

Most times I can release the MT2 on mine without using a hammer, but not always. Would be easier if one had three hands.

Cheers,


Jari