drill bit

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poloidrogo
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drill bit

Post by poloidrogo » April 26th, 2017, 10:42 am

can I use a regular drill bit to drill my bowling balls ?? I know people use a tipped carbide drill bit, but why I can't I use a regular drill bit ?? is there a reason ???

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stevespo
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Re: drill bit

Post by stevespo » April 26th, 2017, 8:25 pm

Yes, you can - but it's definitely not ideal.

I experimented with a set of HSS bits for metal (Silver and Deming, etc) and the edge geometry/rake angle is not ideal for plastics. They can be grabby, especially when dealing with pitches. With a solid mill/drill and a slow feedrate, they will work (but hole accuracy/quality is not great).

Also bowling ball covers and cores contain mineral that will lead to premature wear. You can do a custom grind that will help, but that's additional work.

If you're drilling a few balls for fun, you can try standard bits or possibly even spade bits. For more frequent work, pick up the sizes you need in carbide designed to do the job. Most people will start with their thumb size, and 31/32" for finger inserts. Not a big expense.

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poloidrogo
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Re: drill bit

Post by poloidrogo » April 27th, 2017, 9:43 am

Thanks for your answer , I'm just starter drilling my bowling ball just for fun and I don't really want to spend more money with tons of tools. As you said I will start with the basics drill bit like thumb and fingers grips.


Thanks much !!!!

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Re: drill bit

Post by VLe » April 27th, 2017, 12:38 pm

Normal HSS-bits does straight and accurate holes. They require a bit more care and different methods to operate. Heat is the enemy for cheap drill bits because it causes excessive wear. If you already have a decent bench grinder along with some other gear at home you can sharpen or even modify the drill bits by yourself. Ovaling is harder to do with standard drill bits.

Use slow speeds and cut only about 1/4-1/2" at a time to allow the drill bit to cool down. Use a vacuum cleaner to remove drilled material as you drill so it wont be blocking the drill bit which causes heat. Use a pilot hole especially if you are drilling excessive pitches. Many people starts with small hole and then go gradually up the size until the hole is large enough.

I have found that the good old machinist rule for pilot hole size works great for bowling balls: Use a pilot hole that is same size as the flat part on your drill bit. Attached please find a picture about the measurement.

If you want to drill with ease especially with old balls you can drill a large hole, then plug the hole with ball filler and drill the hole to the plugging material after few hours. Even my cheapest chinese S&D "HSS" drill bit set cuts that like cheese. 8-)
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poloidrogo
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Re: drill bit

Post by poloidrogo » May 4th, 2017, 2:37 am

The reason I'm asking is because I'm a tool die maker and have a lot HHS drill bit so is easier for me to sharpen it and I also have all kind of sizes.

Thank you for your help

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Re: drill bit

Post by Siena » November 29th, 2018, 12:38 pm

regular bits will chip the edges at any speed as a matter of physics. the bowling style flare once it penetrates the shell the bit no longer in contact with the shell until you are pulling the bit out of the ball. a regular bit like this https://mechanicguides.com/best-drill-bit-for-metal/" onclick="window.open(this.href);return false; will continue to be in contact with the shell throughout the whole drilling process so any debris that is coming out can get between the edge and the shell, more heat will be applied to the shell throughout the drill process and the fact the bit stays in contact if the bit moves or chatter even very minimally or slightly you will likely chip the shell around the holes up.......

I don't drill balls but I use to use a lot of shop equipment around resin and fiberglass and we had the same flare tipped bits to avoid tearing up the fiberglass or resin transfer mold. They are definitely worth the money.....you will likely ruing a few balls if you don't use the right tool......you can use a hand drill.

" onclick="window.open(this.href);return false; it's very helpfull video

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KurtHuhn
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Re: drill bit

Post by KurtHuhn » April 14th, 2020, 10:50 pm

the carbide is precision sized to the proper diameter by 1/64", the bits are uniform length, generally sharper to cut cleanly through coverstocks, cost about 3 times more each, but worth it, can be sharpened and re-sized
I use some HSS bits for some of my -/64" sizes after drilling the next size down as a pilot.

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