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Technical Support FAQs

Technical Support FAQs

  1. Can the PCNC mill be purchased without the electrical control cabinet?

    We do not sell the machine frame without controls for several reasons. Unless a machine is completed it cannot be fully tested for precision and quality. In addition, we do not want any confusion between a home-built Tormach mill and professionally finished Tormach mill. Finally, there is no savings to the consumer. Motors, drives, and other control components cost far more when purchased separately.

  2. Does the stepper control system sometimes lose steps?

    Proper engineering of a stepper system is not trivial. The fact that stepper-driven motion control is commonly used on mission critical systems, such as medical equipment, is testament to the reliability and accuracy of the technology. The technology has been given a black eye by a few poorly designed machines offered by others, as well as a large number of hobby CNC projects. PCNC mills and other properly engineered machinery will not lose position in the designed operating envelope. The PCNC 1100 axis system can deliver 850 lbs of force before missing a step, more than enough to break most cutting tools. Step loss is simply not an issue.

  3. Is there a servo driven versional available?

    No. Our stepper motor control system is superior to brush style servos in terms of dynamic accuracy, reliability, durability, and cost. Brush style servos do offer higher speed, but we are not willing to accept the compromises associated with brush servos to achieve a bit of speed. Brushless AC servos do not suffer the problems of brush servos, but their cost is prohibitive. Further details on comparison of axes drive systems can be found on page 7 of our PCNC Design Document.

  4. What is the dovetail surface and will it wear out?

    The plastic surface is PTFE filled acetyl. Common trade names for this type of material are Turcite or Delron AF. The plastic slide surface is not just a coating, but rather a robust bonded strip, about 1/32” thick. This type of slideway was common on mills in the past, but now is only seen on expensive high precision machines such as Hardinge VMCs. The ways must be hand scrapped by experienced technicians. Many machine manufacturers have switched to linear rollers due to labor costs, but manufacturing in China allows us to provide this superior design at a low cost. It’s conceivable that the slideway could get worn out, but it would take a great many hours. To date, we have machines that have been in continuous daily service for over 5 years and have received no reports of worn out slideways . Additional engineering details of the slideway design can be found on page 8 of our PCNC Design Document.

  5. Are replacement parts available?

    We stock all replacement parts, and can provide overnight domestic shipment to the USA, if necessary. We also offer recommended spares kits and individual maintenance parts on our Upgrades & Maintenance webpage. The spares kits are mainly of interest to international customers who do not have an option of overnight shipping.

  6. Why are there two belt positions on the spindle motor?

    The spindle drive is infinitely variable in speed, but there are practical limits because an induction motor delivers very little power at low speed. The motor/spindle ratio needed for 5000 RPM would not be able to deliver any effective cutting power at 150 RPM. By offering two belt positions, our spindle delivers good torque through a wide speed range. Changing belt positions is rarely needed because there is considerable overlap between the high speed and low speed positions. When a belt change is required, it takes less than a minute and requires no tools.

  7. Do you need two wrenches to do tool changes?

    The spindle has a built in spindle lock. This allows a single wrench to be used for tool changing; freeing your other hand to prevent the tool from falling out after it’s loose. There is mechanical interlock on the spindle door, which makes it impossible to forget to remove the spindle lock before starting the spindle. Finally, there is an electrical interlock on the spindle door which prevents the spindle from coming on when you’re in the middle of changing a tool. We also offer a pneumatically activated power draw bar for wrench-free tool changing.

  8. What types of ballscrews are used?

    We use a ground ballscrew, P4 grade with a double nut. P4 accuracy specification is 0.0006” per foot and is 100% inspected using a laser interferometer. Many commercial machines use a lower grade, like P5. P5 screws have a larger tolerance for error and are generally spot inspected, not 100% inspected. Retrofit machines and conversion kits typically use a rolled ballscrew such as Rockford Ball Screws. These are typically ungraded, but are roughly equivalent to C7 or C8 with 0.001" to 0.003" error per foot.

  9. Can I upgrade for increased accuracy?

    We do not offer any accuracy upgrade package, nor would it be practical. The differences between a mill that can consistently deliver 0.001” accuracy and one that can deliver 0.0002” are significant and require changes throughout the machine. There is no magic bullet, or any single component change that will transform the mill into a different beast. Dropping a Corvette engine into a Chevy Impala does not make it a Corvette. Likewise, substitution for higher grade ballscrews, glass scale feedback, or high performance servo will not deliver a significantly higher level of performance.

  10. Do you support older models?/Can I uprade my older model to what is currently being sold?

    Yes and Yes. We support all PCNC models, regardless of what model we are currently selling. Please see our Previous Models webpage for more information, including links to older documentation. At the heart of the PCNC design is the concept of modularity. As technology improves we develop upgrade kits so, if the owner desires, earlier models can be brought up to the performance of current models. We also work hard to make sure that new options, like the Automatic Tool Changer, are compatible with earlier machines.

  11. What motion control does Tormach use?

    Tormach Mills and Lathes alike run on PathPilot - The Next Generation of Tormach Motion Control.

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