My Acme-Gridley screw machines have been real money makers over the years, but all that production takes its toll in wear and tear on the machines. Will I be better off doing major repairs to my current Acmes, looking for deals on good used Acmes, or investing in some type of new machinery?

Which Way Should I Go

Dear Which Way,

Acme-Gridley multi-spindle automatics are well designed to be rebuilt or reconditioned, and worn machines can be returned to good running or like new condition by those qualified to perform that type of work. There are different levels of repair to choose from.

For example, you have a 1-1/4” RA6 Acme machine that needs some work. The heart of an Acme is the spindle carrier, which you might start looking at having rebuilt for around $10,000. This includes rebuilt work spindles, new precision spindle bearings, new front and rear retainers and flingers, and new spindle gears, adjusting nuts and keys. The carrier stem is also ground, and fitted to your re-bushed and bored main tool slide. At the high end of your list of options you have a complete machine rebuild, which for all practical purposes is like a new machine. That will cost in the neighborhood of $100,000 to $150,000, depending on your machine and requirements. Compare that to a price tag of $500,000 or more for a comparable new multi-spindle cam machine.

Another factor to consider is that a rebuilt Acme, when properly maintained, can be run hard for 10 years or more before it will require another rebuild. Most single-spindle CNC machines never get that old before they are obsolete or worn out. Acme-Gridley machines come in a wide variety of models, capacities, and vintages. Some machines in service today predate 1950. With sound castings most of these machines are still great candidates for rebuild or recondition, with just a few old models that are obsolete.

A concern for some shop owners today is a lack of experienced machine repair personnel to remove or re-install a spindle carrier, but most qualified rebuilders can offer contracted field service work to do this for you.

Another option popular with some shop owners is look for an inexpensive, worn, late model machine and have it rebuilt. This could be a good option because its mechanical condition is not a concern as long as the castings are in good shape. But even if a machine is examined by experienced personnel when purchasing, the condition of the spindle bearings will largely be an unknown. So it may be a better option to invest money in a machine that you already have and know.

Acmes are well suited for high production part runs, or running a family of similar parts at moderate volumes, but may not be the best choice for small lot runs unless efforts are made to reduce setup times. Attachments are available for Acmes that allow even complex parts to come off the machine complete. In some cases shops are using Acmes in tandem with single-spindle CNC machines, with the Acme blanking the part and then a robot transferring the part to one or several inexpensive CNCs to finish it off. Your production time may be longer, but in the right type of job the dramatic savings on equipment could very well make up for the additional second or two.

Bottom line, your Acmes still have a lot of life left in them, so if you have the right work for them, rebuilding and refurbishing can definitely pay off.

Dear Shop Doc,

I recently decided to shop around for quotes to rebuild my 1-1/4” RB8 Acme-Gridley.
I sent the RFQ out to three different rebuilders and received three very different prices.
Why is there such a big difference in price from one rebuilding company to the next?

Confused in Cleveland

Dear Confused,

This is a very common situation in our industry today, but a little knowledge can go a long way towards helping you evaluate quotes for your rebuild projects.

Many companies mistakenly assume that the term “rebuild” means the same thing to every supplier. This is not the case, and there can be a great deal of difference between machine tool rebuilders as to what constitutes a machine rebuild. These differences have a substantial impact on what it will cost a rebuilder to do the job, what will actually be done to your machine and what condition your machine will be in when you get it back. For Rebuilder A, it may be standard practice to replace every bearing in the machine, and just about every part with a new part, while Rebuilder B might have the practice of evaluating all of the current parts in the machine and then reusing the ones that pass inspection. One rebuilder may always strip the machine completely down to the castings, inspect them carefully for damage or needed repairs, then repaint the machine inside and out, while another rebuilder may consider that to be more work than necessary.

The differences in opinion about what work must be done when “rebuilding” a machine is the main cause of the wide range of price quotes. Some of the better rebuilding companies offer a written procedure detailing what they do when they rebuild a machine. Many also offer what is commonly called a machine “re-condition,” basically a mini-rebuild, which is also subject to discrepancies from company to company regarding what work is included. A written procedure for machine re-conditioning may also be available.

A great way for a customer to deal with these discrepancies is to write their own detailed outline for what work they want to be performed, and use that as the platform for every rebuilder to bid on. Be sure to include as much detail as possible and outline what is acceptable to you with regard to reusing any current parts on the machine. Also, consider if you want the electrical system to be addressed, if there are attachments that will need to be rebuilt or added, and if there are any other upgrades such as adding a PLC, that need to be outlined. The more detail you have going into the quoting process the more accurate your quotes will be, and the fewer surprises you will have down the road.

David Johnson
Champion Screw Machine Engineering, Inc.

David Johnson is the Rebuild Manager for Champion Screw Machine Engineering, Inc. in Wixom, Mich. He can be reached at djohnson@championscrew.com