Tooling and standards can vary from shop to shop. We build to your external 'as-developed' dimensions and call-outs. A 'flattened' print is helpful (provide one to us if you can), but the dimensions we build to are the finished 'as-developed' spec - because of these tooling differences.

Use these helpful 'expert' or 'ideas' guides - click on the the links BELOW for help and suggestions, and then get your rapidQuote

Want design assistance? We're happy to help out - call us (707) 795-8223 or Contact Us online!

Design Tips & Resources

  • Part size & our capabilities
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    Part Dimensions - Our Capabilities

    Most parts start out as flats, cutout from the punch or laser-press from a standard sheet stock size - typically but not always 4' x 8' or 5' x 10'. All sheet stock thickness is NOT uniform near the edges - an artifact of the rolling process - so your part's FLAT/largest dimension cannot exceed 5/8 in. LESS than the width or the length of the sheet - UNLESS your part is assembled, or welded to form a larger assembly (from smaller sections).

    Formed parts - with more than 3 or 4 bends, smaller than 2in. x 2in. x 2in. - are typically (not always, but often) formed with a progressive die or "4-slide" - a more expensive process. This is typically justified only for high-volume parts, as it always requires custom tooling - so consult us if you are not sure.

    "Bowl" or nose-cone (continuous, no seam) parts - are produced either with deep-drawing or spinning - processes we don't do. Often, we CAN fabricate or weld 'seamless' parts - ducting is a good example - so consult us if you aren't sure, as your design tradeoff may depend on quantity, size, cost or specifications of your part.

  • Bending sheet metal
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    Bending Sheet Metal

    "Bend-deduction" is the length subtracted from the exterior (formed) length - to determine the proper length and width of the flat. "Bend-allowance" is the length added to the flat length or width to arrive at the length (width) your developed part's exterior dimensions (as drawn) must be.

    "Air-bending" the process we use - and used in over 90% of sheet metal fabrication is when the workpiece has 3-points of contact (a punch tip at the center of the bend and either side of the "Vee-die"). In this process the bottom of the metal never flows to the bottom of the vee-die - the bend only goes far enough in the v-opening to compensate for the spring-back of the metal. Adjusting the vee-die and the tool, a variation but different process called "bottom-bending" is very rarely used, but may be called for by your design specifications.

    "Coining" is a specialized process, requiring much more tonnage and different equipment that we don't use.

    If you wish to provide us a flat drawing - your CAD software probably has a table of k-factors or bend-deductions. Since all shops have unique tooling - we advise that you use the k-factors from this table. when we build your part, we'll calculate final flat size from your as-developed dimensions.

    Bending metals is actually a rather physically complex phenomenon. The aesthetic quality, strength, accuracy and the feasibility of the bend(s) you want for your design depend on: the material, the bend- radius, the gauge, the size of the vee-die opening and the force of the press die - Call us for assistance (707) 795-8223 or EMAIL Or, research a little more at these links:

  • Drawing practical forms
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    Drawing Practical Forms

    Your design options, forms and structures are almost unlimited. The press brake is a remarkably flexible tool, but there are some considerations to keep in mind for your design:

    • Bend radius - use the most generous you can afford, the tighter the bend, the greater the tooling cost.
    • Tolerance "stacks up" across multiple bends in the same linear direction - see this link:
      JMMFG Shop Standard Specifications
    • Deep channels or narrow boxes - require special tooling and higher cost. The general rule- of-thumb is the flange (side) length should be no more than 6x the base length - for a channel or 3-sided enclosure.
    • Some forms - like the picture above - are simply not feasible with the press brake and require stamping, deep-drawing or progressive die (4-slide) processes.
    • Even though your CAD program may let you "flatten" your design - the tooling, dimensions, tolerance specifications and the type of material specified will govern whether we can produce your part.
    • Check out this additional link for more design tips about your part's special features:
      Call-outs & critical features
  • Call-outs & critical features
  • When is machining necessary?
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    Is Machining Necessary?

    Avoid specifying 'machining' unless it is absolutely necessary. Here are some guidelines to help you determine:

    • It is NOT our shop practice to "bevel" or break material edges, as is typically the case with machined parts. Why? In 99.5% of cases, you simply don't need it - either our standard tumble debur, or occasionally hand debur of a few features, or, the fact that you are Painting the part eliminates the need. If - as in the case of a sheet greater than .250 in. or some unique feature - you need it - SPECIFY it on the drawing and we'll quote it.
    • Corner Radius. Only necessary if you need tolerance below .005 in., or if your material is > .250 in. DON'T over-specify, but if you need it we will quote it for you.
    • Thread taps. Use PEM® fasteners INSTEAD whenever you possibly can. For material thicker than .250 in., SPECIFY it and we'll quote for you.
    • Holes. We form with a tolerance down to .002 in. (Don't over-specify, if you don't need that precision, specifying it only costs you more money!) If you DO need us to Drill to a tolerance <.002 in., or if your material is > .250 in., SPECIFY the tolerance.
    • Same thing for Milling. The laser and the punch press are capable of very good tolerance, but if you really need to go below .005 in., SPECIFY and we'll quote it.
    • Counter-sink / Counter-bore. The punch does a great job up to .250 in. If your gauge is thicker we'll need to machine them.
  • How to spec PEM® fasteners
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    About PEM® Fasteners

    A self-clinching fastener commonly called a "PEM" (because the most widely-used are made by the PennEngineering company) is an ideal solution whenever a component must be readily replaced and where "loose" nuts and hardware can't easily be reached after assembly. PEMs can be installed by us during fabrication to facilitate component mounting or assembly operations, including those performed in the field.

    When specifying PEM fasteners, there are several important considerations:

    • Make sure to call-out the correct full PEM part no.
    • Specify the hole-size per the PEM catalog recommendation
    • Do not go below the minimum distance hole center to edge -or- distance between features
    • Check to make sure the gauge of material matches the PEM you specify
    • Check that the PEM material you specify is compatible with your material
    • Be sure to let us know to "mask" hardware or mask for grounding hardware if needed (if we are painting your product)

    Here is a helpful link to the wide-variety of PEM fasteners - from weld-nuts to studs and threaded panel screws: PEM® Fasteners

  • Coating, painting & finishing
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    Coating, Painting & Finishing

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    mauris ac, tempus egestas est. Ut ac bibendum est, dictum laoreet quam. Donec ligula turpis, malesuada quis pulvinar vel, viverra nec erat. Nullam est sem.

  • Welding & weldments
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    Welding & Weldments

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    mauris ac, tempus egestas est. Ut ac bibendum est, dictum laoreet quam. Donec ligula turpis, malesuada quis pulvinar vel, viverra nec erat. Nullam est sem.

  • Assembling your product
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    Assembling Your Product

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    mauris ac, tempus egestas est. Ut ac bibendum est, dictum laoreet quam. Donec ligula turpis, malesuada quis pulvinar vel, viverra nec erat. Nullam est sem.