This section covers assorted topics including how to:
- Give special instructions to the machinist
- Import designs from other formats
- Specify the accuracy of your part
- Assign processes to lines
- Trace images
- Optimize cost and time
- Machine existing parts
- Check fit between parts
- Print your designs
- And more
Reducing Cost and Time
The eMachineShop CAD software automatically selects the most economical process given your design and settings such as tolerances.
- Almost all choices you make in each dialogue affect
price. Choose the lowest cost options where possible – especially in Job | Material, Job Settingsand Job | Finishing.
- Avoid checking Job | Settings | Processes | Secondary Process for Intricate Shapes. See Sharp Inside Corners. Features at edges can sometimes be moved to another view to
achievea sharp corner.
- Generally using line type Auto will be less expensive than special processes like Injection Molding for short runs.
- Click Job | Price |
Analyze andview the warnings and advisories to resolve as many machine incompatibilities as practical. This allows the system a better chance of using a lower cost process.
- If you need to apply a finish (powder coat, anodize, plate, etc.) to multiple jobs placed simultaneously, add Comments To Machinist “Apply finishing setup credit for orders placed today.” Your parts will be processed in one batch and the savings passed back to you.
- Do not assume the lowest price combination you tried a month ago is the lowest price today.
- The complex pricing mechanism does occasionally make errors – if you have some experience with the cost of custom parts and feel the price quoted might be an error, please submit your design for review.
- If you imported your design (or part of it) you might find lines made of numerous small line segments. For example, a circle might be comprised of 100 small lines. This can increase price and slow things down substantially. You can determine this by clicking on each line and looking at the status bar. Consider redrawing lines in the eMachineShop CAD so that they are built efficiently.
- Avoid splines. They can occur when you stretch a shape with arcs. Use the Node edit tool to stretch such shapes to avoid conversions to splines.
Very simple parts
If you have a low quantity of a very simple part with loose tolerances, your part might qualify for lower pricing via manual machining as compared to the CNC price computed by the CAD system. Some examples of parts that may be suitable
- If you need a 3D part with
it’smirror image: draw one version; set quantityto total numberof both parts; add as Comments to Machinist “Run half quantity using mirror image.”
- If you have a minor variation between two parts, instead of placing two separate orders consider specifying the variation using Comments To Machinist (e.g. “Change diameter to .503 in for half run”)
- Sometimes you can save by using pre-shaped stock such as
pipeor square tube.
- For injection molding, minimize
useof holes and recesses in the Front, Back, Left and Right views.
- Minimize the number of views used. Slots and other features at edges can sometimes be moved to another view.
- End clamp slots with sharp corners instead of arcs.
- If the design includes a Revolve line with mainly straight line segments along with other features, try rebuilding the shape without using the Revolve line. (Doing so may reduce the number of machining processes from two to one.)
- If the design can be done using the Revolve feature try using that method.
- You can try adding material with positive Z values or removing material with negative Z.
simplerevolved parts you can compare using circles and grooves instead of the Revolve feature.
- You can compare the cost of creating certain features from another view.
- When possible structure your design to minimize Z values. For example, a rectangular block 1 x 1 x 2″ could be drawn in the Top view with a 1 x 1 square having Z set to 2 or a 1 x 2 rectangle having Z set to 1. The second way will usually result in lower cost. For similar a reason, if you imagine laying down your part on a table, usually you will want to draw the Top view as if looking down on your part.
- Since parts are machined according to the way they are drawn, it is sometimes possible to draw a part a different way, resulting in a different machining sequence and hence a different price. You can experiment to find the lowest price method.
- Make sure your parts are really 2D according to the eMachineShop definition of 2D parts.
- If you have a part that is essentially 2D but needs a few countersinks it may be more economical to specify those 3D features using Comments To Machinist.
- Remove edge rounding and edge wall angles if possible.
- For small parts, if 1/16″ fiberglass can be used, ordering a blank circuit board from our Pad2Pad division may be more economical.
- Try to nest (arrange) parts efficiently to minimize material use.
- Some shapes nest more efficiently by including an extra rotated copy. For example, a part in the shape of the letter C is more efficient with two C’s arranged so that one copy is rotated 180 degrees and shifted down 50% and a bit to the right.
- Sometimes parts can be nested to save material. The CAD does not allow nesting fully enclosed shapes however you can add a link with a comment to remove the link.
- Keep the size of 2D parts under 47.5″ x 23″.
- IMPORTANT: Also see the general cost reduction tips.
Reducing Delivery Time
There are several ways to reduce delivery time for custom parts. Here are just a few:
- In Job | Material, check “Show only recommended materials” – those materials are more often in stock.
- Avoid requesting special materials.
- Reduce the number of finishing steps in Job | Finishing.
- Minimize use of Comments to Machinist.
- Click Job | Price |
Tips andresolve as many machine incompatibilities as practical. This can allowyou to run the job on machines with shorter delivery times.
- Pay by credit card.
- For high quantities consider splitting the job to two orders – a small
run withfaster delivery and the main run with slowerdelivery.
Machining limits are the constraints imposed by various manufacturing processes such as maximum size, compatible materials, etc. Often the limits depend on several factors. You can check whether your design is within limits or make test cases to determine limits. For example, you might want to know:
- Can a part 36″ long be machined?
- Is acrylic compatible with machining?
- Is aluminum compatible with nickel plating?
- Can bends be spaced 0.1″ apart?
- How large a part can be cut?
To determine the machining limits relevant to your design:
- Draw your part or a much simplified version of it. For example, simply drawing a rectangle can determine size limits for a 2D design and adding a simple recess pocket can determine size limits for a 3D design.
- Choose Job | Price/Analyze.
- Take note of any warnings or errors.
Note: Warnings shown in Job | Price | Tips do not indicate that your part cannot be manufactured. The incompatibilities listed are only for certain machines – you can proceed with your design.
Also see 3D Capabilities.
You can get miscellaneous useful information about your design. For example you might want to know the weight of your part.
- Choose Tools | Statistics.
You can view detailed information about any line in your design. For example you might need to check the area of the outermost line.
- Select the line.
- Choose Line | Properties or choose Line | Machine to reveal machine settings.
Center of Gravity
The center of gravity of a part is the point at which the part would be balanced if suspended from that point. You can determine the coordinates of the center of gravity of a 2D part. For example, for a rotating part you might want to check if the center of rotation coincides with a rotation axis.
To compute center of gravity:
- Choose Tools | Compute | Center of Gravity.
- A cross appears at the center of gravity point.
- Compute the center of gravity again if you change your design.
This table shows special keyboard shortcuts that can increase your productivity.
|Create new design||Ctrl+N|
|Open existing design||Ctrl+O|
|Save current design||Ctrl+S|
|Print current design||Ctrl+P|
|Undo the last action||Ctrl+Z|
|Redo the last undo||Ctrl+Shift+Z|
|Place selected line(s) to clipboard and clear the line(s)
|Copy selected line(s) to the clipboard||Ctrl+C|
|Paste the clipboard contents to the design||Ctrl+v|
|Nudge selected line(s) up||Up arrow|
|Nudge selected line(s) down||Down arrow|
|Nudge selected line(s) left||Left arrow|
|Nudge selected line(s) right||Right arrow|
|Nudge rotate selected line(s) right||R|
|Nudge rotate selected line(s) left||L|
|Set preferences options||F2|
|Show 3D preview of current design||Ctrl+R|
|Zoom to fir screen||=|
|Zoom to actual size||1|
|Combine selected lines into one group||Ctrl+G|
|Separate a group into its components lines||Ctrl+U|
|Divide selected lines into segments at the points where
|Repeat – duplicate selected line(s) in workspace||Ctrl+D|
|Transform – change position, size, shape of the line(s)||Ctrl+T|
|Specify machine used to manufacture line||F5|
|Select prior line in workspace||Shift+Tab|
|Select next line in workspace||Tab|
|Choose material for current design||Ctrl+M|
|Specify manufacturing , packing, shipment options for current
|Analyze and compute cost of current design||F9|
|Show help contents||F1|
|Choose next side view of design||V|
|Choose prior side view of design||Shift+V|
You can use the CAD software on a PC that is not connected or has a slow connection to the Internet.
To use eMachineShop offline:
- Download the software using a PC connected to the Internet.
- Install the software at your offline PC.
- Choose Edit | Preferences | Pricing | Price File update method | Indirect. Click OK.
- Choose Edit | Preferences | Ordering | Indirect. Click OK.
You can use your offline PC to prepare an order file but you will need to update the pricing file before ordering parts.
Sending Design Images
You can send 2D or 3D images of designs created in eMachineShop to co-workers. For example, you might want to send a drawing to a co-worker in another office.
To send a drawing image:
- Press the Alt+Print-Scr key.
- Paste the image on the clipboard into your email. If your email program does not allow this, paste into a paint or word processing program, save the file, and attach the file to your email.
You can specify to have your parts assembled. For
To have your parts assembled:
- Locate a supplier for any required hardware, adhesives, etc. (e.g. mcmaster.com) and get a price.
- On your drawing use Comments To Machinist to specify your requirement. For example:
- “Bolt hinge here (with arrow pointing to holes) mcmaster.com #123456, $5.00 for pack of 10 – $10 total, eMachineShop supplied”
- “Insert PEM fastener – customer will supply via UPS”
- Affix side panels with
eMachineShop can assemble:
- Inserts: PEM, Helicoil, Slimserts, Keenserts, etc. (first create the thru or blind hole using the normal CAD interface). Customer is responsible for choosing proper hole dimensions.
- Joining parts with adhesive (e.g. an acrylic box)
Machining Existing Parts
Existing parts are parts that you purchased off the shelf, taken out of a mechanism, etc. You can have eMachineShop perform additional machining on existing parts. For example, you might need to add some holes to an engine component. You can begin the process using the eMachineShop CAD or your own CAD application.
To proceed via eMachineShop CAD:
- Make an approximate model of the existing part in the eMachineShop CAD.
- Include the feature to be machined.
- Use Comments To Machinist to indicate which features are pre-existing; any special requirements; and add “For Quotation Only – Customer to supply parts via UPS”.
- Click on a blank area of the drawing and then verify that the comment text color is red.
- Set Job | Settings | General | Quantity to the qty of parts to be supplied.
- Set Job | Material to the closest material to the parts to be supplied.
- Place your order (it will be treated as a quotation request only).
- If you approve the cost, ship your parts to eMachineShop marking the box with the job # from the order confirmation email.
To proceed via another CAD application:
- Make an approximate model of the existing part in you CAD application or create a hand drawing.
- In the drawing include the feature to be machined.
- Use comments to indicate which feature need to be machined and any special requirements.
- Request a quotation and in the comments box indicate “This is for a modification of existing parts to be supplied.”
- If you approve the cost place your order and ship your parts to eMachineShop at the address shown in the footer of this page, marking the box with the quotation #.
You can check if your parts will fit together. For example, you might want to check if a design for a lid will fit on an enclosure you designed.
Here is one method of checking fit:
1. Copy one part onto another:
2. Copy the lines of one part.
3. Paste onto a drawing of another part.
4. Change the copied lines to Comments To Myself.
5. Slide and/or rotate the comment lines into position to check fit.
For parts that rotate together, use the rotate feature along with the above method to see how parts fit during rotation.
Consider tolerance. For example if Job | Settings shows a tolerance of .005″ and a six inch diameter cylinder must fit a hole you must consider that the cylinder could be as large as 6.005 so the hole must be drawn at at least 6.010 since such a hole could be as small as 6.005.
Use tolerance stack analysis.
See also the example design in the bending section.
If you have made numerous changes to a design and are concerned about unintended errors, consider redrawing your design. Doing so can result in a cleaner design and may lower the computed price.
To restart a design:
- Print your design for reference.
- Choose File | New | Blank Design.
- Recreate the design referring to the printout.
Machining & Manufacturing Vocabulary
Read our manufacturing glossary for definitions of terms used in the manufacturing, engineering, and CAD software fields:
2D (Two-Dimensional) – A part design where the Z value of all internal holes and cutouts are air-inside and no edge effects (rounded edges, chamfered edges, sloped walls, or side grooves) are selected and only one view is used (the Top view). 2D parts with bends are still considered 2D.
3D (Three-Dimensional) – A part design where Z values vary or edge effects (rounded edges, chamfered edges, sloped walls, or side grooves) are selected or more than one view is used.
Axis – A principal direction along which the relative movements of a tool or workpiece occur. Three linear axes, occurring at 90° angles from each other, named X, Y and Z.
CAD – (Computer Aided Design) The use of computer applications that allow you to design mechanical parts and other items.
CAM – (Computer Aided Manufacturing) The use of computers to assist in manufacturing.
CNC – (Computerized Numerical Control) The computer control of machines that fabricate custom parts.
Coefficient of friction – The ratio of the friction force to normal force. For example, if it takes 1 lb of force to slide a 10 lb weight along a level surface the coefficient of friction is 0.1. The coefficient depends on the two materials involved.
Creep – The deformation of a part over time when under constant stress.
Fillet – In mechanical engineering, a fillet is a rounding of an interior or exterior corner of a part design.
Friction – Mechanical resistance of motion between two surfaces.
G-Code – The industry standard programming language that controls a CNC machine.
Galling – A type of wear that occurs because of adhesion between sliding surfaces.
Machining Center – Machine tools that are capable of automatically repeating operations such as drilling, reaming, tapping, milling, and boring multiple faces on a workpiece.
Machine Tool – A power-driven machine used to form or shape metal and other materials.
N/C – Numerical Control – The technique of controlling a machine or process by using programmed command instructions provided by coding.
Nudge – The process of moving a line a fixed small distance across the screen using the arrow keys on the keyboard.
Pitch – The nominal distance between centers of repetitive shapes.
Polyline – A line having several segments. For example, a rectangle is a polyline with four segments.
Roughness – A measurable degree of non-smoothness of the surface related to the height of the peaks and valleys.
Set Screw – A threaded fastener typically used to lock a sleeve, collar or gear on a shaft. Set screws are normally headless. Set screw points can have various shapes including cups, cones, ovals, flats and more.
Shank – The section of a bolt between the head and the threads. Sometimes refers to the section of a cutting tool that is held.
Snap – The process of moving one line so it exactly meets a key point on another line.
Static friction – The friction between two surfaces having no relative motion. It is the force required to start relative movement. Also known as stiction.
Tangent – Two curves or lines that are parallel at the point where they meet.
Toolpath – The path that a cutting tool travels to remove material to create a shape.
Torque – A measure of twisting force applied to a fastener, shaft or other rotating member. Force is often measured in newton-metres (Nm) or foot-pounds (ft-lb).
Tolerance – The acceptable variation in measurement.
Z Axis – The third dimension that cannot directly be shown in a flat drawing. The distance out from the drawing towards yourself.
Angle of Thread – The angle between the flanks.
External Thread – A thread formed on the external surface of a cylinder (e.g. a screw).
Flank – The flanks of a thread are the straight sides that connect the crest and the root.
Major Diameter – The diameter of an imaginary cylinder that just touches the crests of an external thread or roots of an internal thread.
Minor Diameter – The diameter of an imaginary cylinder that just touches the roots of an external thread or crests of an internal thread. Also called Root Diameter.
Pitch (threading) – The nominal distance between two adjacent thread roots or crests; or between the centers of other repetitive shapes.
Right-Hand Thread – A screw thread that is tightened by rotating clockwise when viewed from the head. Most screws are right handed.
Rolled Thread – A thread formed by plastic deformation of a rod instead of cutting. Most fasteners are formed this way.
Shoulder Screw – A screw with an unthreaded portion used for more precise and secure locating or as a bearing surface such as in a pulley.
UNC/UNRC – Unified National Coarse is a thread form with a 60 degree flank angle, rounded roots and flat crests. The unified thread is based on inch sizes and was first standardised in 1948. It is the most commonly used thread system used in the majority of screws, bolts, and nuts.
UNF/UNRF – Unified National Fine is a thread form using a finer pitch than UNC. It is used when a higher tensile strength is needed than the coarse thread series; when smaller length of engagement is needed; when a thinner wall is available; and when instruments and parts require fine adjustments.
UNEF/UNREF – Unified National Extra-Fine is a thread form using a finer pitch than UNF. It is used for the same reasons that UNF is used over UNC but for even more stringent requirements.
If you need custom mechanical parts machined – eMachineShop can help!
Simply download our free CAD software, design your part, get an instant price and click to order.
Math functions can be used on the numeric bar in place of fixed values.
The following binary operators are supported:
- Addition +
- Subtraction –
- Multiplication *
- Division /
- Modulus mod
- Raise to the power: ^
The following single parameter functions are supported:
- Absolute value: Abs ()
- Arc Tangent: Atan ()
- Cosine: Cos ()
- Sine: Sin ()
- Exponent: Exp ()
- Natural logarithm: Ln ()
- Round to nearest integer: Round ()
- Square root: Sqrt ()
- Square: Sqr ()
- Round down to nearest integer: Trunc ()
The following two parameter functions are supported (semicolons between parameters):
- Minimum: min (x;y)
- Maximum: max (x;y)
Note: Angles are in radians
- 5/4 = 1.2
- 10 mod 3 = 1
- 2 ^ 3 = 8
- Round (1.9) = 2
- Sqrt (2) = 1.414…
- Square (2) = 4
- Trunc (1.9) = 1
- Min (5,2) = 2