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(External Links: Gear replacement guide)
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{{DISPLAYTITLE:Grizzly G8689 Manual Mini-Mill}}
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= Central Machinery 44991 Manual Mini-Mill =
  
 
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Contact [mailto:facilities@atxhs.org Danny Miller], [mailto:hr@atxhs.org Joe Ngo], [mailto:ops@atxhs.org Robert Ristroph] to get a walk through on the operation and safety for those tools. The owner, Andrew Darling is no longer in the hackerspace, but is continuing to allow us access to his tools.
 
Contact [mailto:facilities@atxhs.org Danny Miller], [mailto:hr@atxhs.org Joe Ngo], [mailto:ops@atxhs.org Robert Ristroph] to get a walk through on the operation and safety for those tools. The owner, Andrew Darling is no longer in the hackerspace, but is continuing to allow us access to his tools.
  
=== Status ===
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=== Installing Collets ===
As of January 2018, the mini mill is broken in multiple ways:
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[[File:Mini_Mill_R8_Keyway.jpg|thumb|200px|Keyed spindle]]
* The [//www.grizzly.com/parts/GEAR-30T/P8689138 P8689138] gear (Ref #138) is missing.
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[[File:Mini_Mill_Locking_Pin.jpg|thumb|200px|Locking pin]]
* The high/low gear lever doesn't engage. Possibly transmission gears [//www.grizzly.com/parts/TRANSMISSION-GEAR-WIDE/P8689080 P8689080] and [//www.grizzly.com/parts/TRANSMISSION-GEAR-NARROW/P8689140 P8689140] (Ref #80 and #140) have been sheared off.
 
* The Z axis won't move. The coarse/fine adjustments both turn, but it feels like the rack and pinion teeth are skipping.
 
  
=== Features ===
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* R8 collets are located in the '''metal cabinet''' next to the mill.
* Dovetail column
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* Not all spindles are keyed, but ours is. Line up the '''collet keyway''' with the '''spindle key''' when inserting a new collet.
* Safety shut off switch
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* Insert the '''locking pin''' (aka. tommy bar) into a hole on the right side of the black housing around the spindle. Rotate the spindle by hand while gently pushing in the locking pin until it engages and locks the spindle. Now you can use a 17mm wrench to tighten and loosen the drawbar.
* Adjustable depth stop
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* '''DO NOT LEAVE THE LOCKING PIN IN THE MILL.''' You'll break something if you try to start the mill while the locking pin is still engaged. A good habit is never taking your hand off of the pin while it's engaged, similar to never taking your hand off of a chuck key.
* Fine feed head control
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* Don't hold the spindle nut with a spanner wrench when tightening or loosening the draw bar. The spindle nut is held in place with only a setscrew. It also preloads the spindle bearings, and if it were to move and tighten, then it could cause excessive wear on the bearings.
* Geared drive
 
* Clear guard on spindle
 
* Rubber chip guards on ways
 
* Zero setting dials read in inches
 
* Adjustable dovetail ways on column
 
* 3/8" and 1/2" collets
 
* 1/2" drill chuck
 
* Two T-nuts
 
* Made in an ISO 9001 factory
 
  
=== Specifications ===
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=== Transmission ===
* Motor: 3/4 HP, 110V, single-phase
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* Switch between high and low gear only with the '''motor off'''.
* Spindle taper: MT #3
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* '''Jiggle the spindle''' by hand when switching gears to make sure the gear teeth fully engage.
* T-slots: 2 @ 1-1/8" centers, 7/16" wide
 
* Head travel: 7-1/2"
 
* Head tilt: 45° L/R
 
* Max. distance spindle to table: 11-1/2"
 
* Swing: 12-3/4"
 
* Table travel (longitudinal): 7-5/16"
 
* Table travel (cross): 4"
 
* Table size: 3-5/8" x 15-3/4"
 
* Range of speeds: Variable, 0–2500 RPM
 
* Approximate shipping weight: 149 lbs.
 
  
 
=== External Links ===
 
=== External Links ===
* [http://www.grizzly.com/products/Mini-Milling-Machine/G8689 Grizzly G8689 Mini Milling Machine]  
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* [https://www.harborfreight.com/two-speed-variable-bench-mill-drill-machine-44991.html Central Machinery 44991 Manual Mini-Mill]  
* [http://cdn0.grizzly.com/manuals/g8689_m.pdf Instruction Manual]
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* [https://manuals.harborfreight.com/manuals/44000-44999/44991.pdf 44991 Instruction Manual]
* [http://cdn0.grizzly.com/partslists/g8689_pl.pdf Parts List]  
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* [https://littlemachineshop.com/Info/MiniMillUsersGuide.pdf Generic Mini-Mill User's Guide]
 
* [http://anivo.com/reed/G8689_cont/g8689_cont.htm Grizzly G8689 mini-mill motor controller repair] (includes schematics)  
 
* [http://anivo.com/reed/G8689_cont/g8689_cont.htm Grizzly G8689 mini-mill motor controller repair] (includes schematics)  
* [http://www.grizzly.com/products/g8689/parts Replacement Parts]
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* [http://theminimachineshop.com/Technical/R8%20Spindle%20Kit.pdf Spindle Removal & Reassembly]
* [http://aspinock.com/7x10minilathe/Kinda-Old/MiniMill/grizzly%20mini-mill.htm Removal and Replacement of the Grizzly Mini-mill Spindle Head Gears]
 
 
* [http://www.mini-lathe.com/Mini_mill/Main/mini-mill.htm www.mini-lathe.com (Mini-Mill)]
 
* [http://www.mini-lathe.com/Mini_mill/Main/mini-mill.htm www.mini-lathe.com (Mini-Mill)]
 
* [http://littlemachineshop.com/reference/CuttingSpeeds.php#Milling Feeds & Speeds]
 
* [http://littlemachineshop.com/reference/CuttingSpeeds.php#Milling Feeds & Speeds]

Latest revision as of 17:19, 26 March 2018

Central Machinery 44991 Manual Mini-Mill

 

ATX HackerSpace Pages relating to the mini-mill
G8689.jpg
Central Machinery 44991 Manual Mini-Mill
Milling101
Edit this template
Grizzly G8689 Manual Mini-Mill.jpg

This mini-mill is to be used primarily for metal or plastics. Special instructions are needed if using this mill on steel. Do not use on wood.

See also: Taig Mini-Mill

Requires Approval to Become Qualified for Operation

Contact Danny Miller, Joe Ngo, Robert Ristroph to get a walk through on the operation and safety for those tools. The owner, Andrew Darling is no longer in the hackerspace, but is continuing to allow us access to his tools.

Installing Collets

Keyed spindle
Locking pin
  • R8 collets are located in the metal cabinet next to the mill.
  • Not all spindles are keyed, but ours is. Line up the collet keyway with the spindle key when inserting a new collet.
  • Insert the locking pin (aka. tommy bar) into a hole on the right side of the black housing around the spindle. Rotate the spindle by hand while gently pushing in the locking pin until it engages and locks the spindle. Now you can use a 17mm wrench to tighten and loosen the drawbar.
  • DO NOT LEAVE THE LOCKING PIN IN THE MILL. You'll break something if you try to start the mill while the locking pin is still engaged. A good habit is never taking your hand off of the pin while it's engaged, similar to never taking your hand off of a chuck key.
  • Don't hold the spindle nut with a spanner wrench when tightening or loosening the draw bar. The spindle nut is held in place with only a setscrew. It also preloads the spindle bearings, and if it were to move and tighten, then it could cause excessive wear on the bearings.

Transmission

  • Switch between high and low gear only with the motor off.
  • Jiggle the spindle by hand when switching gears to make sure the gear teeth fully engage.

External Links