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" I think of John Prosock as a value added partner and I would recommend JPM to everyone except my competition." Kody, SKF

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Prosock Machine Shop Talk

April 14, 2009

Prosock Machine featured in Cutting Tool Engineering Magazine

Recently, Bill Kennedy of Cutting Tool Engineering magazine interviewed our shop Foreman, Claude Kennedy, for his monthly piece called, “Part Time.”  Bill asked Claude to describe a particularly challenging CNC machined part that would be an example of our long line of success stories.  Here’s the article:

Holding Firm

John Prosock Machine, Inc. is a Quakertown, Pa., job shop that handles prototype machining as well as production and assembly jobs. Founded in 1982, the shop today has 10 mills, 13 lathes, and about 30 employees. Typical production runs range from 100 to 2,000 pieces, and the shop serves a wide range of customers; “we pretty much do anything,” said plant manager Claude Farrington, “medical work, driveline components, heavy equipment, parts for remote-control cars, you name it.” The shop machines a variety of materials including common steels and aluminums as well as plastics, titanium, and other exotic alloys.

Describing the machining of a prototype aluminum trunion housing for a powerboat steering system, Farrington said the actual machining of the complex-appearing part was not too difficult; “it was a matter of trying to figure out how to hold it.”

The roughly 11 ½”-long, 5 ½”-wide housing was intended to be mounted on a boat’s transom and house an electronic linear actuator. It is part of a system designed to provide instant steering response when activated by controls at the helm, eliminating the slow reactions of a cable system.

Prosock Machine received a DXF file from its customer and loaded it into the shop’s Mastercam CAM package to program milling operations. Lathe work was programmed at the machine.

The housing was machined from a 12″ x 6″ x 3 ½” 6061T6 aluminum block. It was clamped with the long dimension standing vertical in a Kurt vise with aluminum soft jaws on an Excel 810 VMC. One end of the finished housing would feature a single 1.850″-dia., 3.850″-long boss, but to start, two identical bosses were machined side-by-side. “We machined two so that when we flipped it over we could use them to align the part in the vise. Later we cut the one off that we didn’t need,” Farrington said.

The twin bosses were machined with a 1 ½”-dia. HSS endmill, run at 3,000 rpm and a 30 ipm feed rate, taking a 4″ length of cut. Farrington described the toolpath as “a figure 8 around the bosses,” stepping down 0.200″ on each pass.

Then the housing was flipped over in the vise and one of the bosses was located against a stop. On the other end of the finished housing would be two bosses that were not identical, being of different diameters and offset from each other by 70˚. One boss, in line with a boss machined earlier, was 2.100″ in diameter. The other boss was 1.514″-dia. Because this second set of bosses were closer together than the first pair, smaller endmills were used to machine them. The bosses were roughed with a 7/8″-dia. HSS hogmill and finished with a ¾”-dia. HSS endmill, both run at 1,200 rpm and 10 ipm with a 4″ loc. The two bosses were 1.360″ long, but one was set back (x “?) deeper in the part than the other.

Water-soluble coolant was applied throughout the machining process. Farrington described the HSS tools the shop employs as “generic,” and said all the solid-carbide tools it uses are from Mill Monster, while inserted milling and turning tools are from Kennametal.

When milling of the second set of bosses was complete, the smaller diameter one was drilled and reamed. A 1 1/16″-dia. HSS drill, run at 600 rpm and 4 ipm feed and pecking each 0.200″, drilled to a depth of 7.7″. As the tool pecked in and out of the workpiece, flood coolant from the spindle cleared the chips from the hole. A 1.103″-dia. reamer then finished the hole to a tolerance of +/- 0.0004″. At this point, the housing was removed from the mill and the extra boss created in the first operation was cut off with a band saw, leaving a short stub to be faced off later.

Next, the part was clamped horizontally in the vise and a 3″-dia. shell mill, run at 2,500 rpm and 20 ipm, face milled the housing to height of the next feature, a 3.5″-wide, 2.7″-long, 0.72″-deep pocket that would hold the actuator electronics. A ½”-dia. carbide endmill run at 3,500 rpm and 25 ipm, roughed out the pocket, leaving 0.050″ extra stock on the sides and 0.010″ on the floor. Then a ¼”-dia. carbide endmill finished the side profiles and bottom. A very small pocket in the bottom of the larger feature required the application of a 1/32″-dia. carbide endmill. Outside each corner of the pocket a hole was drilled 0.433″ deep with a 0.114″-dia.(?) drill, and tapped with an M3.5 x 0.6 tap.

The next operation involved milling the back of the housing. The part was flipped over in the vise, the 3″-dia. shell mill faced away excess material, and a ½”-dia. carbide endmill roughed and finished the details. The sharp edges of a lug created in the operation then were rounded with a radius mill.

Next, the housing was moved to a Eurotech turning center for turning, facing, and boring. With the 2.100″-dia. boss clamped in the chuck, the (now) single 1.850″-dia. boss on the other end of the part was turned down to a 1.765″ diameter for a length of 1.653″, using a DNMG 431 insert run at 700 rpm and a feed rate of 0.008 ipr. The same tool then faced off the remaining stub of the extra boss removed earlier. Farrington said the eccentric shape of the part posed no problem in the lathe; “It was a pretty good size diameter to hold on to, and we didn’t spin it at very high rpm.” A NTF2R threading insert then cut an M45 x 1.5 thread at the end of the boss.

Next, a 1-5/16″-dia. drill, employed at 400 rpm and 0.010 ipr with a 0.250″ peck cycle, drilled the boss out to a depth of 9.665″. A 1″-dia. KMT boring bar run at 500 rpm and 0.007 ipr finished the bore to a diameter of 1.37″, +/- 0.002″.

The part then was turned end for end in the lathe and chucked on the 1.850″-dia. boss, behind the thread. A 13/16″-dia. drill made a 2 ¼”-deep hole in the 2.100″-dia. boss at 500 rpm and 0.005 ipr, employing a 0.250″ peck. Then a 5/8″-dia. boring bar created a chamfer and a counterbore in the front end of the hole, and behind that cut a bearing diameter of 1.0004″, +/- 0.0004″.

For the final operation, the housing was clamped horizontally in a Haas indexer mounted on the table of the Excel VMC, again held on the 1.850″-dia. boss. A ½”-dia. carbide endmill, run at 2,000 rpm and 18 ipm, milled a series of lengthwise flats, positioned via the indexer at 10˚ intervals. Then the same endmill circular-interpolated two 0.775″-dia., 0.354″-deep counterbores in the end of the 2.100″-dia. boss. After machining, the housing received a 0.005″ – 0.010″ thick blue anodized coating.

Farrington said that total machining time for each part was roughly 1½ hours. He termed this job a typical small volume (“The customer wanted three, we made five”) prototype job, involving ongoing consultation with the customer’s engineers as the design evolved during the prototyping process.

For more information about John Prosock Machine, Inc., call (215) 804-0321 or visit

March 24, 2009

Visit us at the Valley Forge, PA “Design 2 Part” show

Filed under: Uncategorized — Tags: , , — admin @ 11:37 am

Most of us are facing the current economic difficulties with the mixed bag of fear and dogged determination.It has caused us here at John Prosock Machine to reevaluate many of our CNC mill and lathe operations.It also has motivated us to look at fresh ideas on how we can better expose our quality machining services to the market.

One way we are doing this is by participating in the upcoming “Design 2 Part” show coming up on April 21 & 22.

We will be hosting a booth at this event and will have the opportunity to expose our great machining services to many engineers and purchasing agents.

For over 30 years Design 2 Part has been providing a venue for company owners, buyers and engineers to connect with the best suppliers in the business.

If you are a OEM looking to expand your vendor base, or just network with others in the manufacturing industry, this show is for you.We invite you take advantage of this great opportunity for your company.And, we would appreciate you stopping by our booth to see us.

Click on free pass and it will take you to our site where you can get a pass to get in.

February 18, 2009

Are you looking to buy CNC machines?

There are a lot of places that sell quality CNC lathe and milling machines, but few have the great reputation as a trusted source for machine shops as Midwest.  If you want to expand and keep machining costs to a minimum consider a used CNC lathe or mill machine.  Check out Midwest Machinery.



Welcome to Midwest Machinery!  We hope you will find exactly what you’re looking for in a machine tool, be it fabrication, CNC machining or support, we strive to offer the very best that the used machinery market has to offer.



Midwest Machinery is a stocking machine tool dealer with inventory on site at our Franksville, Wisconsin facility. Our 25,000 square foot warehouse can accommodate all sizes of machine tools while having the added advantage of viewing them under power. We are happy to accept trade ins, as well as consign your equipment on site to assure you the best return on your equipment for sale.


Our staff has a combination of machine tool experience in both fabricating and metal cutting machinery, as well as CNC equipment.  If you don’t see what you need on our site, please let us know, chances are we know where to find it immediately!
We have a knowledgeable staff that will strive to deliver quality products based on your needs, and assist you from start to finish.  We don’t just want your business;  we want your repeat business.  We also have a very knowledgeable full-time Service Technician on staff to teach, train, maintain, and troubleshoot machine tools.

Feel free to contact us by phone, fax or e-mail if you need additional assistance or other information not provided here at our website.  We sincerely thank you for your time and consideration.


Midwest Machinery, Inc.
21303 Omega Circle
Franksville, WI 53126

Copyright � Midwest Machinery, Inc. 2008

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