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Carmex Single Threading Insert holder - For Carbide External/Internal Threading Inserts - SR0021H21

SKU:SR0021H21

The Carmex Single Threading Insert Holder SR0021H21 is a precision tool holder designed to accept carbide external and internal threading inserts for CNC milling. Part of the Mill-Thread family, ... Read more ↓
Insert Size21
Shank Diameter20
Shank MaterialSteel
Reach40
Overall Length94
Minimum Bore Diameter21
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£127.84
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In Stock— only 1 left
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The Carmex Single Threading Insert Holder SR0021H21 is a precision tool holder designed to accept carbide external and internal threading inserts for CNC milling. Part of the Mill-Thread family, it enables reliable, repeatable thread milling on modern CNC machines without the need for traditional taps or dies.

It’s built for shops and professionals—engineers, machinists, and operators—who need fast, consistent threading performance. With this holder, you can leverage indexable carbide inserts to boost cutting speeds, improve productivity, and reduce overall tooling costs on threaded jobs.

  • Internal coolant bore: Delivers coolant directly to the cutting edge, helping reduce insert wear, improve chip evacuation, and produce cleaner thread finishes.
  • Engineered for Mill-Thread carbide inserts: Supports high-speed threading with multi-tooth carbide inserts, delivering faster cycle times and reliable seating for consistent threads.
  • Cost-effective tooling option: Lower tooling costs compared with taps and dies, while maintaining threading quality and repeatable results across multiple jobs.

When you pair the Carmex SR0021H21 with compatible threading inserts, you gain a versatile, low-downtime solution that streamlines your threading workflows. The internal coolant bore helps maintain stable cutting conditions, while the holder’s robust build and Mill-Thread compatibility deliver dependable performance across a range of materials. This means fewer tool changes, more productive cycles, and consistent thread quality that you can trust on every job.

Insert Size 21
Shank Diameter 20
Shank Material Steel
Reach 40
Overall Length 94
Minimum Bore Diameter 21
Flutes 1
Neck Diameter 16.5
Insert Screw S21
Torx Key K21
Extension N/A

What time are Protool open?

We are open Monday to Friday between 8:30am and 5pm.

Do you offer Free Next Day delivery?

Yes! We offer Free Next Day delivery via Royal Mail Tracked 24 on all orders over £50 ex VAT*. We also offer Free DPD Local Next Day delivery on all orders over £100 ex VAT*.

We also offer the following:

  • Royal Mail Tracked 24 — £5.90 (FREE on orders over £50 ex VAT*). Order before 4:30pm for next day delivery. No signature required.
  • DPD Local Next Day — £8.00 (FREE on orders over £100 ex VAT*). Standard next day delivery to UK mainland addresses.
  • Royal Mail Special Delivery — £12.50. Guaranteed delivery before 1pm the next working day.
  • DPD Saturday Delivery — £25.00. Must be ordered on Friday before 4pm. Pre-12pm delivery.

For delivery to Scottish Highlands & Islands, Northern Ireland, Republic of Ireland, or overseas locations, additional charges apply. Please see our delivery page for full details, or call us on 01732 887 334.

*T's & C's and exclusions apply. Please see our delivery page for more information on all our services.

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Staff are very helpful and interested in providing a good service making us the customer feel valued.
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honest about stock and prices are competitive.
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Staff are very helpful and polite.Goods that were in stock were dispatched same day and back orders were quick in coming through .
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Buying experience
Phone requests are handled quickly and without any fuss. The website is easy to use and straightforward to order from. It’s especially helpful that it shows real‑time availability, so we don’t need to call to confirm whether parts will arrive.
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Full Range: Carmex Single Threading Insert holders - For Carbide External/Internal Threading Inserts

View full collection →

You are viewing SR0021H21. Click any other SKU to view its full details.

Product SKUInsert SizeShank DiameterReachOverall LengthMinimum Bore DiameterNeck DiameterPriceStock Order
SR0009H12 122014859.57.5£91.20 5 days
SR0010H12 122016859.97.6£100.72 5 days
SR0012F14 14202075128.9£79.68 5 days
SR0014H14 1420258514.511.2£87.62 5 days
SR0017H14 142030851713.4£98.02 5 days
SR0018H21 212030851814.4£121.04 5 days
SR0021H21 Viewing212040942116.5£127.84 In Stock
SR0029J30 3025501102922.4£156.08 5 days
SR0048M40 4040781534835£212.46 5 days

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