Powermatic Millrite MVM

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Owner/Loaner: User:Jim
Make/Model: Powermatic Millrite MVM (google)
Arrival Date: 11/2019
Does it work?: Yes
Certification Needed?: Yes
Contact: CNC Warden
Floorplan: 2D
Manual: Manual
Powermatic_Millrite_MVM.png



Powermatic Millrite MVM

Overview

This particular "Millrite" is what is known as a 'knee-and-column, turret-type' vertical milling machine.

It is a manual machine. It has sufficient weight, power, and rigidity to perform a wide-range of general-purpose metal-cutting (milling and drilling) operations. Vertical mills of this type have been ubiquitous in job shops for the past century.

In the capable hands of a knowledgeable user, a sequence of specific harder-metal rotating tools can be safely brought into controlled interference contact with a softer metal workpiece. The resulting cutting action produces metal chips and finished parts. The action is similar to wood-cutting machines that produce sawdust, but the metal-cutting forces are much higher and less forgiving. A sequence of subtractive milling operations transforms the original workpiece stock to create specific round and flat surface features to precise tolerances. Dimensional tolerances measured in single-digit thousandths of an inch (+/-.001") can be repeatedly produced.

In the inexperienced hands of a neophyte user, such a mill is highly dangerous. An unsafe milling process can quickly result in serious personal injury and catastrophic damage to the machine.

Learning to use such machines has traditionally been a multi-year, on-the-job, experience-based process. Individuals went through a lengthy 'apprentice' period and then spent their entire career working on a single machine to develop the knowledge-base and 'feel" for this highly-skilled trade craft and become a 'machinist' or a 'tool-and-die maker'. There are many ways to be inattentive, careless, do it wrong, and get into trouble. It is a constant challenge to be attentive, diligent, do it right, and stay safe.

History of this machine

Cincinnati is credited as the home for early versions of this type of machine starting in the 1880's. This particular Millrite was made in Cincinnati, in the Oakley neighborhood, on Brotherton Avenue at a company that was founded in 1915. It is serial number 711226. It was the 1226th machine made in 1971,

This is JimD's personal machine. It is on indefinite consignment to Hive13 for gentle use by considerate members. Jim bought it from a small machine ship in the New York state finger lake area in 1980, It has been in JimD's home shop for the past 40 years.

It features an essentially simple but strong construction. It was offered in several sizes with multiple alternative head, ram, and power configurations.

The product line was intended as a low-cost competitor to the established (and somewhat larger) Bridgeport machines made in Connecticut.

Evolution of the Cincinnati company that made this machine:

  • 1915: The United States Machine Tool Co. was founded in Cincinnati, Ohio.
  • 1947: United States Machine Tool Co. became the US Machine Tool division of Ransohoff Co.
  • 1948: US Machine Tool division of Ransohoff Co. merged with Burke Machine Tool and became US Burke Machine Tool Co.
  • In the 70s: US Burke became part of the Powermatic/Houdaille conglomerate
  • 1979: following in a KKR leveraged-buyout, the Houdaille company went bankrupt and was lost to history.

The company's history is mentioned in From Industry to Alchemy: Burgmaster, A Machine Tool Company by Max Holland. This book was named by Business Week as one of the ten best business books of 1989. We highly recommend this book to anyone interested in the decline of the American manufacturing industry. The book's focus is Burgmaster Corp., which was also acquired by Houdaille; because of the Houdaille connection there is some information on Powermatic as well.

Evolution of the product line:

  • Millrite model MV (1960-’64)
  • Millrite model MVI (1965-’67)
  • Millrite model MVN (1967-’75)

This millrite is a versatile manual machine. It has hand-feed on the X (table) Y (cross-feed), and Z (knee) axes. The standard model had a table with a working surface 7" x 27" with 16" of longitudinal travel. The feed screws are of generous proportions, a full 7/8" in diameter, of Acme form and run through bronze nuts. The cross feed travel of the table was a useful 8" - whilst the head could also be moved in and out of its swivelling support through a range of 12.5". The combination of these movements means it can bring its cutter as close as 4" to the main column yet reach as far away as 16.5". With the head set to swivel, the cutter was able to sweep along an arc with a maximum radius of 25" (12.5" minimum) and cover, in conjunction with table's longitudinal movement, a length of some 62". With the quill retracted, and the knee lowered, a maximum clearance of 17.75" was available between the spindle nose and table - although 5-inch raiser blocks were available to increase this as required.

Fitted as standard with as simple, V-belt drive head powered by a 1 hp, 1800 rpm motor, six well-spread spindle speeds were available in each direction of 335, 575, 970, 2550, 3075 and - very useful for running smaller cutters - 4535 rpm. However, at least three different motors are known to have been offered: a 0.75 h.p. with speeds from 250 to 3400, a 1 hp 1200 rpm unit that gave 250, 430, 725, 1160, 2300 and 3400 rpm - and another 1 h.p. type of 900 rpm with a range of 185, 320, 540, 860, 1700 and 2500 rpm.

For the standard specification miller, the floor space requirement is approximately 60" x 50" and the weight is around 1100 lbs.

The spindle quill taper is R8.

User Certification

We do Mill and Lathe certification on an as needed basis. Email the warden to request certification. Only the following people are permitted to certify you on the mill:

Certification Goals – Don’t hurt yourself. Don’t hurt the machine.

  • Mill safety and setup
  • Tool selection for milling operations
  • Holding parts using the machinist vice and parallels
  • Change tools and set spindle speeds
  • “Zero” the X, Y and Z axis using the DRO
  • Perform basic facing cuts on steel
  • Mount and secure work using parallels and hold downs
  • Demonstrate understanding of Backlash

In preparation for certification please; Read the manufacturers manual and study the excellent materials from Case Western

http://engineering.case.edu/sears-thinkbox/use/mills

Take the milling quiz.

https://www.proprofs.com/quiz-school/story.php?title=mill-quiz When you have a score of 100% print out the certificate and contact the CNC warden for your certification check ride.

Current Status (2019-11-11)

The mill is re-assembled and connected to power, available for limited initial use by members that are certified to use this tool. JimD has consigned a | starter kit of tooling for use with the mill. JimD is also working on a 'Good2Go Mon' badge-activated power box for this machine and other certified-user machines at the Hive. You are encouraged to use the machine, but are cautioned to be SAFE for your sake, and for the sake of the machine. Things can get out-of-hand quickly if you do not know what you are doing.

Please contact Jim at jim@hive13.org and/or cell 513.300.5164 to share your questions and plans for use of this mill.

Related Tooling (2019-11-11)

Traditionally, tooling is sub-divided into two categories; 'Durable' tooling and 'Perishable' tooling.

  • Durable tooling can include a wide assortment of work-holding devices such as vices, parallel bars, step blocks, clamp sets, and other fixturing that can be general-purpose, or part specific. The re-usable parts of cutting tools (collets, end-mill holders, drill chucks, and such) are also considered to be durable tooling. Metrology items such as dial indicators can also be considered as durable tooling.
  • Perishable tooling includes all the different consumable items such as end mills, drills, cutters, and inserts. The Hive owns a variety of high speed steel end mills which were purchased used on eBay. You are welcome to use these. They are in a box under the Enco mill labeled 'Good enough'. If you damage one, report it to broken (at) hive13 dot org.

The number of items in a resulting kit of durable and perishable tooling can grow quite large and be very expensive, often growing to exceed the cost of the machine itself. While JimD has consigned a starter set of tooling, the Hive may consider to vote to procure additional tooling if there is sufficient group interest. You should consider to procure your own perishable tooling, particularly if you have special, or high volume needs.

There are many considerations in selecting the proper tooling for a given part and cut.

  • For the workpiece fixturing, RIGIDITY is the primary consideration. The part must be held VERY SECURELY to avoid deflection and vibrations from the cutting forces that can be heavy. An associated consideration is clearance for the range of motion of the cutter.
  • For the durable tooling, RIGIDITY and clearance considerations remain of primary importance. Rigidity typically means short and stubby tool holders for stiffness and vibration resistance purposes.
  • For the perishable tooling, RIGIDITY and clearance are still primary considerations, but there are many added factors to consider. Selecting even a 'simple' end mill requires proper consideration of multiple factors based on the desired cut. These factors include tool material (typically carbide, or high-speed steel); tool coatings (such as TiN); tool diameter; tool length; flute length; number of flutes (typically two flutes (center cutting) or four flutes (NOT center cutting); and corner radius.

Even with selection of the proper workpiece fixturing, tool holder, and cutter, there are additional milling process decisions to make. These decisions include choice of climb or conventional milling, axial depth of cut, radial depth of cut, chip load per tooth, and related tool RPM and feedrate. It is very easy to apply forces that can break steel tools at the shank. Such incidents over-stress the machine structures, lead screws, and spindle bearings. Flying pieces of loose tool steel can be a personal hazard.

There are many web resources to learn about tooling. This Wikipedia page is a start.

WTB (Want to Buy)

  • Storage rack for R8 tooling

Maintenace

  • Way Oil (Vactra #2)-- [1]
  • 1"x2" 6061 Aluminum (Soft Jaw material) [2]

Sites to buy from for cheap

Gallery

Milled Items

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Mill

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iGaging scale on Z axis of mill

Resources

Manuals & Guides

Books

Supplies & Parts

General Information

Someone else who picked one up (Ours is nicer)