Mill purchase

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Tucker Tomlinson, Zlatan Klebic

History

September 25th, 2013 - discussion open on member list

October 15th, 2013 - proposed vote date

October 15th, 2013 - vote passed 37 yes, 0 no, 3 present

Goal

We want to see a large manual mill capable of basic and advanced work brought into PS1 with the associated tooling to make it a useful tool for the space.

Background

Currently Pumping Station: One owns no functional machining equipment. While the shop appears well served, all functioning equipment in the shop is on loan from the members. Given the extended interest and support of the members for the machining area it is high time that the space recognizes and supports the machine shop. Space ownership of the tool should also facilitate certification, as initial certification will not be bottlenecked at the owner. The membership has already pledged funds in excess of $3600 to facilitate purchase of a mill, which indicates the desire of the membership for this equipment.

Parallel fundraising

This vote does not preclude further fundraising to reduce the impact a mill purchase would have on the finances of PS1. With the passage of this vote members could additionally be encouraged to donate directly to PS1, earmarking the funds for the mill purchase, rather than contributing to the pledges that will be used for tooling. This would allow parallel efforts to raise funds to offset the purchase cost. Since there is no official authorization to purchase a mill these efforts cannot reasonably start until after this vote.

Ongoing expenses

While this vote would explicitly authorize a single payment, this type of tool incurs ongoing costs. In order for a milling machine to remain useful a stock of sharp end-mills must be kept on hand. While end mills do wear out with use, they are not single use items. Consequently these must be treated like the drill bits kept in the wood and metal shops, or saw blades for the Saw-Stop, and periodically replaced/sharpened. This will constitute an ongoing expense to the space. Specialty bits like ball end, or corner rounding bits should be purchased by the members using them. A small collection of stock should also be made available for certification and spur of the moment projects. These things will increase the operating costs of the metal area, but only in proportion with the usage of the machine.

Why not a CNC mill?

CNC mills of the size we are considering here can be very dangerous, both to their operators and to themselves. Nothing stops a user from programming a CNC mill from cutting itself into chunks. Further CNC mills do not have the sensors to detect when they are cutting something they aren’t supposed to. This makes them additionally dangerous as operators are frequently tempted to reach into the work area to clear away chips or add cutting fluids. This can result in the machine cutting into whatever entered the working area unexpectedly. Further, many CNC conversions are made by removing some of the hand controls and replacing them with motors. This reduces their usefulness as manual mills. Additionally, most CNC mills come from production environments. This means that they are more likely to be used very hard before re-sale, and are more likely to have problems with slop and wear that are not evident on an initial inspection. Finally, in order to program a CNC mill safely, the operator needs an understanding of how mills operate. Since this understanding is most readily gained by using a manual mill, it makes sense for PS1 to purchase a manual mill first, and then expand with a CNC mill if that capability is desired.

Language

We the membership of Pumping Station: One add a milling machine(1) to the list of discretionary capital expenditures in the Pumping Station One budget. If this vote passes the board of Pumping Station One will be authorized to expend up to but not exceeding $4000 to directly purchase a manual milling machine. This amount shall include the costs of shipping the purchased machine to Pumping Station One. This vote will make a milling machine the first item on the list of discretionary purchases as established in the current budget. This spending authority will expire upon purchase of a mill or at the time a new budget is passed, whichever occurs first.(2) Upon completion of this purchase a full account of the monies spent and equipment purchased will be presented by the Treasurer of Pumping Station One to the membership via the mailing list within 1 month of the purchase date. PS1 will not be responsible for purchasing additional tooling to make the mill functional. Interested members have already pledged more than $3600 towards the purchase of a quality milling machine. If this vote passes, these pledged funds will be used to purchase a set of tooling(3) that will ensure the mill is capable of most member projects.

Footnotes

1) For the purposes of this authorization, the milling machine purchases should be substantially similar to the description here:

  • A vertical milling machine with capacity similar to a Bridgeport Series I, J head mill.
  • This mill should have a table of 42”x9” capable of travel in three axes.
  • The head of the mill should have a quill capable of at least 3” of travel, and capable of accepting collets with capacity of 1” preferably in a common style such as R8 or 5C.
  • The mill should have a central lubrication system, either manually pumped or continuously driven.
  • The motor should be of 1Hp or greater capacity with wiring requirements of no more than 240V 3Phase, as this is the most substantial voltage available at PS1.

Condition of the mill:

  • The mill should be in good working order, requiring no substantial repairs to be put into service.
  • The mill should be observed under power at the time of purchase.
  • The linear joints should operate smoothly, with no loose area near the center of travel or binding near the ends of travel.
  • Backlash should be minimal, Less than 30 thousandths of an inch with less than 10 thousandths being optimal.
  • The machine should be free of rust, and should not have been de-rusted via chemical or mechanical action.
  • The paint on the machine should be in good condition, with minimal chipping.
  • Special consideration should be given to mills equipped with Digital Read Outs (DROs) and power feeds installed, as these are costly retrofits.
  • Additional tooling included with the mill is desirable, but any additional tooling should not substitute for any of the preceding requirements of quality or capacity.
  • This machine should NOT be equipped for use as a CNC operated mill.

2)Since the purchase of this machine may need to be resolved on short notice in order to secure a good deal it makes sense to have a single person in charge of actually making the purchase rather than attempting to track down a board member with access to PS1 funds once a suitable machine is found. After speaking to the board, the following strategy is the simplest way to accomplish that:

  • The board will write a check for the full amount authorized by the specified member.
  • This member will then be responsible for making the purchase of the mill from their personal accounts and then presenting the board with a receipt for the purchase cost as well as a refund of the portion of the allocated funds not actually spent on the purchase of the mill.
  • The responsible member will sign an agreement written by the board that formalizes the above.
  • At the time of this proposal the responsible member will be Tucker Tomlinson. If Tucker Tomlinson is for any reason unable to complete these duties, a new responsible member will be selected by the metal shop area host and approved by the board.

3)The following is a list of the desired tooling, in the order that it will be purchased using the member pledges. Items from this list will be purchased until no more funding from the member pledges is available. If all items on the list are purchased and funds are still available from the member pledges, the remaining funds will be given to the metal shop area host in order to expand the collection of bits and stock metal available to members for use with the mill. (The prices listed here reflect the experience and web-searches of Tucker Tomlinson, and may not reflect the true cost of these items. The costs listed here should be taken only as a ballpark reference for the cost of each item)

  • 3 Phase wiring to current hot-metals area for mill hookup (estimated $200)
  • Vise (estimated $300)
  • collets (estimated $300)
  • Jacobs chuck (estimated $50)
  • Hold down set(estimated $150)
  • Set of 4 flute square end-mills (estimated $75)
  • set of 2 flute square end mills (estimated $75)
  • initial collection of aluminum stock (estimated $300)
  • Digital read out kit (DRO) (estimated $800)
  • rotary table (estimated $500)
  • indexing head (estimated $800)

Vote

passed with 37 yes, 0 no, 3 present (quorum minimum was 29)



The board adopted Mill Cash Advance Agreement agreement on 10/22 with Tucker Tomlinson and will have a copy of it signed and filed and give Tucker a check to begin shopping very soon.