Tap your parts as low as $0.50 per park in bulk.
Save up to 70% or more with quantity discounts! We calculate quantity discounts based on several factors including material, operation type, number of operations on each part and number of duplicate parts. Our app will automatically provide quantity discounts based on your order.
Check out our processing page for information about typical lead times for tapping and other services.
When deciding which thread size to call out in your design, keep these rules of thumb in mind:
UNC (Unified National Coarse)
Standard for most applications. Easier to tap, stronger in thinner materials, and more resistant to stripping in softer metals.
UNF (Unified National Fine)
Finer pitch than UNC. Better when space is limited, or when working with harder materials that can support more threads per inch.
Metric (M)
Based on ISO standards. Typically chosen if your project already uses metric hardware.
At SendCutSend we automatically resize holes to perfectly fit the tap you need! That being said you’ll still want to reference our hole size chart when calculating the minimum distance required from other cut features.
We’ll need the center of any tapped holes to be at least the following distance from other cut features: tap hole size/2 + the minimum tap hole-to-edge distance for the chosen material.
The minimum hole-to-edge distance is measured from the edge of the tapped hole to the nearest cut feature, and the specification can be found on each individual material info page by stock thickness.
Below is a chart of SendCutSend’s available tap sizes. Each tap size is paired with the required through-hole size that will be needed in your design.
Use the formula above to make sure there’s sufficient distance between tapped holes and other cut features to ensure optimal performance for your applications.
| Thread/Tap Size | Hole Size (in) | Hole Size (mm) |
| 4-40 | 0.091″ | 2.32 |
| 6-32 | 0.116″ | 3.00 |
| 8-32 | 0.138″ | 3.51 |
| 10-32 | 0.164″ | 4.17 |
| 1/4-20 | 0.209″ | 5.31 |
| 1/4-28 | 0.221″ | 5.62 |
| 5/16-18 | 0.266″ | 6.76 |
| 5/16-24 | 0.278″ | 7.07 |
| 3/8-16 | 0.323″ | 8.21 |
| 3/8-24 | 0.341″ | 8.67 |
| 1/2-13 | 0.435″ | 11.05 |
| 1/2-20 | 0.459″ | 11.66 |
| M2 x 0.4 | 0.065″ | 1.66 |
| M2.5 x 0.45 | 0.083″ | 2.11 |
| M3 x 0.5 | 0.102″ | 2.60 |
| M4 x 0.7 | 0.134″ | 3.41 |
| M5 x 0.8 | 0.170″ | 4.32 |
| M6 x 1.0 | 0.203″ | 5.16 |
| M8 x 1.25 | 0.274″ | 6.96 |
| M10 x 1.5 | 0.344″ | 8.74 |
Please note, the hole sizes per tap size listed in our thread/tap size chart are specific to our tapping service. If you plan to tap parts when they get to you, we recommend referencing the hole size charts provided by the manufacturer of the taps you will be using.
Ideally, you want as much thread engagement/depth of thread as possible. Depending on the application, you may be able to get away with much less. For the best strength, you should try to aim for 1-1.5X the bolt diameter to depth ratio.
For example, an 8-32 bolt should have roughly (0.136”-204”) thread/material depth.
We hope this guide helps you design your parts for greater success with us, and we ask that you take the time to check out the other guidelines pages to make sure everything looks great. In the end, it will save us all a tremendous amount of time and energy!
If you have specific questions regarding your design and they aren’t covered in our guidelines, don’t hesitate to reach out to our support team. Our friendly and talented folks will get back to you as soon as possible!
We offer tapping on CNC machined parts in a wide range of thread sizes. Use the chart below to find the correct hole size for your tap. Please do not model threads into your design — just include the proper hole diameter, and we’ll take care of the rest.
| Metric | Hole Size | SAE | Hole Size |
| M2 x 0.40 | 1.600mm | 4-40 | .0890″ |
| M2.5 x 0.45 | 2.050mm | 6-32 | .1065″ |
| M3 x 0.50 | 2.500mm | 8-32 | .1360″ |
| M4 x 0.70 | 3.300mm | 10-24 | .1470″ |
| M5 x 0.80 | 4.201mm | 10-32 | .1590″ |
| M6 x 1.00 | 5.001mm | 1/4-20 | .2010″ |
| M8 x 1.25 | 6.701mm | 1/4-28 | .2130″ |
| M10 x 1.50 | 8.499mm | 5/16-18 | .2570″ |
| M12 x 1.75 | 10.201mm | 5/16-24 | .2720″ |
| 3/8-16 | .3125″ | ||
| 3/8-24 | .3320″ | ||
| 1/2-13 | .4219″ | ||
| 1/2-20 | .4531″ |
Please note, the hole sizes per tap size listed in our thread/tap size chart are specific to our tapping service. If you plan to tap parts when they get to you, we recommend referencing the hole size charts provided by the manufacturer of the taps you will be using.
For best results, thread depth should not exceed 3× the tap diameter (3XD).
Example: A ¼-20 tap has a .25″ diameter, so the recommended maximum thread depth is .75″.
This guideline ensures strong threads while reducing the risk of tool breakage.
Keep tapped holes centered at least 1.5× the tap diameter away from any part edge or shoulder feature.
Example: A ¼-20 tap should be at least .375″ from the hole center to the edge of the part.
Exact clearance can vary depending on the design, so all tapped holes are reviewed on a case-by-case basis.
When adding tapped holes, make sure there is enough clearance for the tap and collet to reach the feature. If tool access is restricted by nearby geometry, we may not be able to tap the hole as requested.
When preparing your design:
Please note: All tapped holes will be right hand threaded
Tapping is available on all CNC machined parts. Our part sizing for CNC machining is as follows:
We hope this guide helps you design your parts for greater success with us, and we ask that you take the time to check out the other guidelines pages to make sure everything looks great. In the end, it will save us all a tremendous amount of time and energy!
If you have specific questions regarding your design and they aren’t covered in our guidelines, don’t hesitate to reach out to our support team. Our friendly and talented folks will get back to you as soon as possible!
