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How to consistently make circle openings for dog training scent box

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Forum topic by BB1 posted 04-02-2017 06:06 PM 1513 views 0 times favorited 15 replies Add to Favorites Watch
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BB1

847 posts in 682 days


04-02-2017 06:06 PM

Short question is how to cut consistent 5 inches circle openings in plywood.

Here’s the long version of the question…I am working on some “scent boxes” – these will be for training our pup as a diabetes alert dog (my husband has type 1 diabetes). The boxes are about 15 inches long and 12 inches tall and 12 inches wide. I used ¾ inch plywood for the main frame of each box and thinner plywood for the top and bottom. The top will serve as a sliding lid so it can be opened to place the scent tin or a blank inside. I need to cut a circle opening in the plywood sides and the top. The idea is to have a consistent opening so all the boxes (I have three in progress right now) will be “the same” so the only difference will be the scent (or lack thereof) placed inside. Thus the openings need to be as much the same in size/shape/location as possible. The openings are planned to be about 5 inches. I am hoping some of the LJ community will have suggestions. Right now I’m thinking my only option is following a pencil line with my jig saw (and a steady hand) – I don’t have a band saw. Any other thoughts would be welcome!


15 replies so far

View TheFridge's profile

TheFridge

8287 posts in 1320 days


#1 posted 04-02-2017 06:11 PM

Hole saw or circle cutter in a drill press maybe?

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View MrUnix's profile

MrUnix

5979 posts in 2033 days


#2 posted 04-02-2017 06:16 PM

Or a router with a circle jig… either store bought or homemade.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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BB1

847 posts in 682 days


#3 posted 04-02-2017 06:22 PM

I like that idea as it would be very consistent…but only have a small bench top drill press (new so I have only used it on a couple projects so far) so not sure if it could handle a cut that size. And I am not sure I could get the pieces in place given its size (looking for the holes centered somewhat on the panels). Had thought about trying overlapping holes with the smaller bit I have currently but was afraid it would be inconsistent.


Hole saw or circle cutter in a drill press maybe?

- TheFridge


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BB1

847 posts in 682 days


#4 posted 04-02-2017 06:25 PM

I thought about that but talked myself out if it…would this provide a smooth finish with plywood? Likely as good as a jigsaw or better as I think more about it.


Or a router with a circle jig… either store bought or homemade.

Cheers,
Brad

- MrUnix


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TheFridge

8287 posts in 1320 days


#5 posted 04-02-2017 06:58 PM

Yup

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View wichman3's profile

wichman3

49 posts in 455 days


#6 posted 04-02-2017 07:53 PM

When I need large dia consistent hole I turn to this set:
http://www.harborfreight.com/34-in-5-in-carbon-steel-hole-saw-set-18-pc-69073.html
Reasonable price and the larger holes work with DC applications. I’ve use a hand drill (corded) for the 5 inch, but a drill press would be easier.

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BB1

847 posts in 682 days


#7 posted 04-02-2017 09:39 PM

Got the ok to go with a rectangle opening. Made a little plywood template. Jigsaw for the rough opening and then used double sided tape to attach the template to the panels. Trimmed up at the router table with a flush trim bit with guide bearing. Not perfect but hopefully will serve the purpose. Assembly may have to wait until next weekend! Do wish I had that hole saw kit as would be faster (although wouldn’t work with my little drill press due to limits on surface space )- thank you for the suggestion on that set at HF.

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BB1

847 posts in 682 days


#8 posted 04-02-2017 09:40 PM

On my list of items to add to the shop – looks like a handy set.


When I need large dia consistent hole I turn to this set:
http://www.harborfreight.com/34-in-5-in-carbon-steel-hole-saw-set-18-pc-69073.html
Reasonable price and the larger holes work with DC applications. I ve use a hand drill (corded) for the 5 inch, but a drill press would be easier.

- wichman3


View HerbC's profile

HerbC

1684 posts in 2693 days


#9 posted 04-03-2017 03:19 AM

BB1,

Please do not take this as a slam, just want to point out that if you had fully considered the design requirements before starting the actual build of this project you could have pinned down the location and size of the hole and used the drill press and a hole saw to produce the circular hole before assembling the box…

Anyway, sounds like you came up with a reasonable alternative solution.

Be Careful!

Herb

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

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BB1

847 posts in 682 days


#10 posted 04-03-2017 11:00 AM

For sure – although the drill press I have (it is a small table-top unit) would not have worked as the clearance is insufficient to allow the hole to be placed where needed. Not sure if a hand-held drill can be safey used to make such a large hole. Maybe a reason to add a larger drill press to my wish list! I haven’t done any assembly yet – want to do some pre-finishing (likely some areas painted to continue to promote the similarity of the boxes in appearance). Weekends are about the only time to squeeze in some time in the shop; hopefully can have them done soon as puppy training is ongoing.


BB1,

Please do not take this as a slam, just want to point out that if you had fully considered the design requirements before starting the actual build of this project you could have pinned down the location and size of the hole and used the drill press and a hole saw to produce the circular hole before assembling the box…

Anyway, sounds like you came up with a reasonable alternative solution.

Be Careful!

Herb

- HerbC


View DrDirt's profile

DrDirt

4407 posts in 3576 days


#11 posted 04-03-2017 01:04 PM

Any concerns about the scent in the box remaining… such that when you put in the control, it still “smells positive”?

Just wondering how you get the scent out of the wood? even though the canister contains it, the box becomes like a hotel room that has been smoked in.

-- “The two most important days in your life are the day you are born and the day you find out why.” Mark Twain

View MikeB_UK's profile

MikeB_UK

88 posts in 868 days


#12 posted 04-03-2017 01:59 PM



For sure – although the drill press I have (it is a small table-top unit) would not have worked as the clearance is insufficient to allow the hole to be placed where needed. Not sure if a hand-held drill can be safey used to make such a large hole. Maybe a reason to add a larger drill press to my wish list!

I’ve just used a hole cutter similar to this
http://www.toolstation.com/shop/p44999?mkwid=s7OiAu1nB_dc&pcrid=142481253537&pkw=&pmt=&product=44999&gclid=CI6HoLm4iNMCFRNmGwodzOcJZg

Very easy to use, using a hand brace, looks decidedly unsafe to use with an electric drill.
Worked a lot better than I expected.

-- I've worked out how to sharpen, now how do you get blood out of pine?

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BB1

847 posts in 682 days


#13 posted 04-03-2017 05:01 PM

Good question. We are learning from various sources, including, of course, youtube videos. Use of these boxes appears common. I had questioned the lingering scent issue. Time will tell! Learning experience for us as well as our pup. Have been very impressed with her ability to find the tin with the scent in it (she is just 6 months old and loves this “game”).


Any concerns about the scent in the box remaining… such that when you put in the control, it still “smells positive”?

Just wondering how you get the scent out of the wood? even though the canister contains it, the box becomes like a hotel room that has been smoked in.

- DrDirt


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BB1

847 posts in 682 days


#14 posted 04-09-2017 08:54 PM

Finally finished the scent boxes. Turned out pretty similar so hopefully will serve the purpose. Opening on the front is for the pup and the one on top is to give treats. Lid slides back and then divider will keep the scent tin in place.

View wichman3's profile

wichman3

49 posts in 455 days


#15 posted 04-09-2017 09:14 PM


For sure – although the drill press I have (it is a small table-top unit) would not have worked as the clearance is insufficient to allow the hole to be placed where needed. Not sure if a hand-held drill can be safey used to make such a large hole. Maybe a reason to add a larger drill press to my wish list!

I ve just used a hole cutter similar to this
http://www.toolstation.com/shop/p44999?mkwid=s7OiAu1nB_dc&pcrid=142481253537&pkw=&pmt=&product=44999&gclid=CI6HoLm4iNMCFRNmGwodzOcJZg

Very easy to use, using a hand brace, looks decidedly unsafe to use with an electric drill.
Worked a lot better than I expected.

- MikeB_UK

!!DO NOT USE THIS CUTTER FREE HAND!!
and if you are not used to this type of cutter, make a circular shield to go on top (a clear plastic coffee can lid works well). It is difficult to see the outside edge of a fly cutter while it’s running, hence the shield.

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