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Bowdrie · 06-05-2024, 17:47

A previous post recommended ~60rpm on the bit.
That's not bad for a 5/8ths bit, the charts generally show a little faster, no big deal.
Will your drill press really slow down to no more than ~100rpm?
And even at that speed can you put a piece of pipe over the handle to get the needed pressure without breaking the handle?
Can an assistant apply a more-or-less continuous amount of cutting oil?
Actually WD-40 is not bad for stainless, although the thicker-bodied oils used for threading operations, (containing sulfur,) are better and less messy.
A previous post mentioned no pilot hole.
Not so fast, much has to do with the shape of the web on the bit.
Look at your bit, depending upon web shape/geometry the web can do from some to none in cutting.
If it does none, a pilot just about the size of the web thickness or a small bit under will really lessen the amount of pressure needed.
After my long winded post, can you not find a real machine shop to do the work?
Alternately, a fabrication shop with a 50 ton punch press can make a clean hole without distortion, a good shop will even make a square hole that can use a carriage bolt. so much cleaner than hex-head bolts on chainplates.
There ARE reasons for Bronze chainplates other than corrosion.

GILow · 06-05-2024, 17:55

Quote:

Originally Posted by Bowdrie

A previous post recommended ~60rpm on the bit.
That's not bad for a 5/8ths bit, the charts generally show a little faster, no big deal.
Will your drill press really slow down to no more than ~100rpm?
And even at that speed can you put a piece of pipe over the handle to get the needed pressure without breaking the handle?
Can an assistant apply a more-or-less continuous amount of cutting oil?
Actually WD-40 is not bad for stainless, although the thicker-bodied oils used for threading operations, (containing sulfur,) are better and less messy.
A previous post mentioned no pilot hole.
Not so fast, much has to do with the shape of the web on the bit.
Look at your bit, depending upon web shape/geometry the web can do from some to none in cutting.
If it does none, a pilot just about the size of the web thickness or a small bit under will really lessen the amount of pressure needed.
After my long winded post, can you not find a real machine shop to do the work?
Alternately, a fabrication shop with a 50 ton punch press can make a clean hole without distortion, a good shop will even make a square hole that can use a carriage bolt. so much cleaner than hex-head bolts on chainplates.
There ARE reasons for Bronze chainplates other than corrosion.

Yep, I hear you on all of this.

Just to be clear, one more time.

I have an adequate but not great setup for drilling. A bit too fast and a bit low on pressure. But with the use of the Tefolex cutting oil and a Sutton INOX bit I’ve been knocking out half inch holes with no difficulty.

I was hoping to find an equivalent drill bit in 5/8ths but that is proving difficult.

At this stage, unless one of the leads here comes through I think the CNC water jet option will be the easiest and fastest solution.

I don’t want to buy any more tools if I can avoid it (we live on the boats and and are planning to set sail very soon) and I don’t have a drill sharpener for a start.

But thanks again for the description of how to drill stainless.

dlj · 06-05-2024, 19:13

Quote:

Originally Posted by GILow

I think my Bordo split point drills are 118mdegress and they do work well. But my set only goes to 13 mm. I haven’t actually tried them on stainless though, except for very light work.

Give them a try. You may quite like them. Typically you can only get them at industrial supply sources, but I did find a set at Harbor Freight (low cost tool store in the US - for those that may not know) once...

dj

**skipperpete** · 06-05-2024, 19:31

Hey Matt, if drill chatter is the problem while getting the ⅝ to start in the ½” pilot, consider doing a ⅝ hole in a bit of alloy plate or a piece of hardwood, clamp it all to the drill table and that ⅝ pilot should steady the bit and avoid the ugly chatter

GILow · 06-05-2024, 19:37

Quote:

Originally Posted by skipperpete

Hey Matt, if drill chatter is the problem while getting the ⅝ to start in the ½” pilot, consider doing a ⅝ hole in a bit of alloy plate or a piece of hardwood, clamp it all to the drill table and that ⅝ pilot should steady the bit and avoid the ugly chatter

Not the problem in this case, but it is one I’ve experienced in other jobs. I like the solution, noted for future reference thank you.

GILow · 06-05-2024, 19:39

Quote:

Originally Posted by dlj

Give them a try. You may quite like them. Typically you can only get them at industrial supply sources, but I did find a set at Harbor Freight (low cost tool store in the US - for those that may not know) once...

dj

Yep, another case of our US cousins having great shopping options. You lucky buggers.

coopec43 · 06-05-2024, 19:59

Quote:

Originally Posted by GILow

Yep, another case of our US cousins having great shopping options. You lucky buggers.

I always planned ahead so that if an item such as fasteners, pump, electrical switch, circuit breaker, control panel etc etc were not available "off the shelf" I would buy from an online manufacturer/supplier outlet, eBay, Bias or Amazon.

I never felt constrained by lack of shopping options but then I did a lot of searches using google, eBay, Amazon, Alibaba.....

I'm not sure what advantage "our US cousins" have quite frankly

**Wotname** · 06-05-2024, 20:24

Quote:

Originally Posted by GILow

I think my Bordo split point drills are 118mdegress and they do work well. But my set only goes to 13 mm. I haven’t actually tried them on stainless though, except for very light work.

They might be 118 degrees but almost all spilt point drill are 135 degrees.

There is a lot of hype about 135 degree drill angles but most of it is marketing hype. It is true 135 degree is better for SS but not as much as the marketing suggests. The main problem with 135 degree points is that you really need to have a spilt point to get the benefit and it is bloody hard for the DIY guy to create a spilt point when sharpening bits at home. At least it is bloody hard for Wottie to sharpen and maintain a spilt point, others may be more adept...

For SS work a well sharpened 118 degree will outperform a 135 degree that has lost it's spilt point although a perfect 135 degree with a split point intact will alway outperform a perfect 118 degree.

Drill sharpening has become a lost art although there seems to a resurgence on the YT scene. Equally important is the chisel angle and perhaps more important is the relief angle. The best I can aim for is about 120 degrees with a relief of around 15 to 20 degrees and I that whatever chisel angle I end up with.

**Wotname** · 06-05-2024, 20:32

Quote:

Originally Posted by Bowdrie

..........
A previous post mentioned no pilot hole.
Not so fast, much has to do with the shape of the web on the bit.
Look at your bit, depending upon web shape/geometry the web can do from some to none in cutting.
If it does none, a pilot just about the size of the web thickness or a small bit under will really lessen the amount of pressure needed..........

This ^^

Especially after one has re-sharpened the bit a little less than perfectly!

Sailorichiban · 06-05-2024, 20:39

Cobalt tipped hole saw! Likely the same as a fabrication outfit might use.

GILow · 06-05-2024, 20:45

Quote:

Originally Posted by Wotname

They might be 118 degrees but almost all spilt point drill are 135 degrees...

They are 118, I just checked. Bordo’s Quicksilver range. Nice drills for everything else I’ve used them on. But my set maxes out at 13 mm and they don’t even come close to the performance of the Sutton INOX series drill bit I have in half inch.

GILow · 06-05-2024, 20:46

Quote:

Originally Posted by coopec43

I always planned ahead so that if an item such as fasteners, pump, electrical switch, circuit breaker, control panel etc etc were not available "off the shelf" I would buy from an online manufacturer/supplier outlet, eBay, Bias or Amazon.

I never felt constrained by lack of shopping options but then I did a lot of searches using google, eBay, Amazon, Alibaba.....

I'm not sure what advantage "our US cousins" have quite frankly

Perhaps if you’d spent less time on Amazon you might actually have gone sailing.

dlj · 06-05-2024, 20:50

Quote:

Originally Posted by Wotname

They might be 118 degrees but almost all spilt point drill are 135 degrees.

There is a lot of hype about 135 degree drill angles but most of it is marketing hype. It is true 135 degree is better for SS but not as much as the marketing suggests. The main problem with 135 degree points is that you really need to have a spilt point to get the benefit and it is bloody hard for the DIY guy to create a spilt point when sharpening bits at home. At least it is bloody hard for Wottie to sharpen and maintain a spilt point, others may be more adept...

For SS work a well sharpened 118 degree will outperform a 135 degree that has lost it's spilt point although a perfect 135 degree with a split point intact will alway outperform a perfect 118 degree.

Drill sharpening has become a lost art although there seems to a resurgence on the YT scene. Equally important is the chisel angle and perhaps more important is the relief angle. The best I can aim for is about 120 degrees with a relief of around 15 to 20 degrees and I that whatever chisel angle I end up with.

Guess I didn't know there was any kind of "hype". I just have worked with them compared to 118 degree drill bits. Working in stainless, it's a better choice. I agree the compound curves are difficult to achieve by hand.

dj