# 20MM Dog Hole question

**URL:** <https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409>\
**Category:** Wasteboard\
**Created:** [September 20, 2022, 10:32pm UTC](https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409 "2022-09-20T22:32:14Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![CygnusA](https://avatars.discourse-cdn.com/v4/letter/c/439d5e/32.png) [@CygnusA](https://forum.onefinitycnc.com/u/CygnusA)\
**Post date:** [September 20, 2022, 10:32pm UTC](https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409/1 "2022-09-20T22:32:14Z")

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I am making a spoil board to use with my existing 20mm dogs. I have a spoil board file I paid for that is made for 3/4in dogs, but the hole is oversized by about .020in. I am adjusting the holes in my software to use the metric dogs, but am questioning the .020in oversize. It seems a little loose?

Should I oversize the 20mm holes or just cut them exactly to 20mm ?

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**Author:** ![Matticustard](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/matticustard/32/9039_2.png) [@Matticustard](https://forum.onefinitycnc.com/u/Matticustard)\
**Post date:** [September 21, 2022, 12:47am UTC](https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409/2 "2022-09-21T00:47:59Z")

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For my 3/4" Kreg bench dogs, I made the holes 0.765" — or 0.015" oversized — and they are perfect. But I didn’t get this number from the internet. I created a test file with a number of different size holes and checked to see which worked best before cutting into the spoil board. I would highly recommend you do the same if you want the best results.

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**Author:** ![Chris874](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Chris874](https://forum.onefinitycnc.com/u/Chris874)\
**Post date:** [September 21, 2022, 2:38am UTC](https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409/3 "2022-09-21T02:38:02Z")

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I use the 20mm Bench Dogs. Mine have threaded centers, so I have a little 8mm threaded knob that helps pull them out of my MDF wasteboard.

Like Matticustard, I did a test piece making holes, varying the diameter by a couple of thou, until I found the best snug fit.

You don’t want them super tight as MDF will vary a little with changes in humidity.

 ![](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/2X/c/c8d3026ac8d5bbf30e62da89d4edc4a843c5b600.jpeg)

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**Author:** ![mtannerdesigns](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/mtannerdesigns/32/9309_2.png) [@mtannerdesigns](https://forum.onefinitycnc.com/u/mtannerdesigns)\
**Post date:** [September 21, 2022, 9:20am UTC](https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409/4 "2022-09-21T09:20:23Z")

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Be cautious of your bit selection, both programming and physically. 6mm versus 1/4", etc.

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**Author:** ![Alphonse](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/alphonse/32/3408_2.png) [@Alphonse](https://forum.onefinitycnc.com/u/Alphonse)\
**Post date:** [September 21, 2022, 12:56pm UTC](https://forum.onefinitycnc.com/t/20mm-dog-hole-question/15409/5 "2022-09-21T12:56:43Z")

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As already mentioned, test holes will get you the right answer. Be sure and use the same bit when you cut the Waste Board.