Drilling Tips

[ncburch22]

I purchased two 3/4" D-ring shackles for my front bumper. The holes in the bumper for the shackles measure 3/4", but the shackle pin is slightly larger therefore the pin will not slide through the hole. I'm kind of nervous about drilling through the powder coated bumper, but I will do it. I got a step-bit, but I'm not sure if it will work? I read to use a low RPM setting on the drill when cutting through hard metal to prevent it from getting too hot and potentially melting it to an uneven surface. Should I try using a regular bit or use the 3/4" step-bit? I only need to widen the hole just enough to let the pin slide through.

 

[bbyer]

Probably just the paint thickness - use a file.

It may be that it is just the paint thickness that is not allowing the pin to push through. I would first just use a rat tail, (round), metal file and try that first. 1/16" inch all around is 1/8" smaller hole and with powder coat, it can be that thick or none at all, sort of thing.

A regular bit will be OK, but I hope it is just the paint as you are probably reaming at least 3/4" of material x 2, so that would not be alot of fun.

Some tables I have suggest the pin should be a bit under 0.75" so if the drilled hole is 0.75" clear, it may just be the paint. I cannot attach the single pdf file due to forum rules.

 

[ncburch22]

Thanks. I had to use a 7/8" bit and cutting oil to bore the hole out. The pin still did not fit so I sanded it down.

 

[bbyer]

3/4" does have the 7/8" pin

I reread my shackle tables and resized that you probably purchased the 4.75 tons working limit shackle which has the 7/8" diameter pin, and a bow diameter of a nominal 3/4".

I shackle with the 3/4" pin diameter usually has a working load limit of 3.25 tons and a bow diameter of 5/8".

Sounds like you successfully solved the problem however. The cutting oil was the right move. Thanks for the update.

 

[ncburch22]

Silly me, at first I had not used cutting oil and right away I could see my $30 HSS bit being chewed away by the steel. Luckily I didn't go too long without the oil. I'll keep these measurements in mind next time I go for a rear shackle. Thanks.

 

[bbyer]

Links to Van Beest shackle site.

The first link below is a 40 page pdf from the Dutch manufacturer Van Beest who make bow shackles and the like, Land Rover sized and bigger. These are the guys who make the shackles that lift the Cole etc.

The second link shows some pictures of shackles bigger than any Land Rover made. The whole website is very interesting with regards to lifting and towing. Under Products / English, there are a number of downloads, the Shackle one below being one of the catalog downloads. The numbers for your shackle are on page 14 of the pdf in both metric and inch sizing.

http://www.vanbeest.com/public/files/catalogue/en/Chapter01_Shackles.pdf

http://www.vanbeest.com/products/application_pictures