drill size for m8 rawl bolt

mullinr2 · 22-11-2017 11:38am #1

Quick question that I hope will be answered. I'm installing a wall mounted pull up bar in my garage. I'm going to use an m8 rawl bolt. What size drill bit should I use? Looking at various threads people seem to suggest a 14mil bit. Would that not make an awful big hole for a 8 mil screw? I don't want it to be too lose.
Another question. How are u meant to know if your drilling into the brick or mortar joint between bricks. Is it just pure guess work
TIA

the_pen_turner · 22-11-2017 12:35pm

if everything is plastered it is just a guess if the joint I there or not

it depends on the actual fixing. is it an actual rawl bolt. as in a shield anchor. if it is then it probably is a 12mm or 14mm.
your best bet is to hold the bit up to the end of the bolt and look at it. it has to be the same size or slightly larger but not too much.

bonzodog2 · 22-11-2017 1:23pm

I think I used this size years ago, had a 17mm nut, used a 16mm drill. Just measure it unexpanded.

mullinr2 · 22-11-2017 1:40pm

https://m.youtube.com/watch?v=X9DkX4N9DKU

This is the rawl bolt I'm going to use

the_pen_turner · 22-11-2017 1:43pm

bonzodog2 wrote: »

I think I used this size years ago, had a 17mm nut, used a 16mm drill. Just measure it unexpanded.

don't measure it expanded. it wont get any grip then

tooManyChoices · 22-11-2017 1:51pm

You might consider using concrete bolts or concrete screws instead?

Concrete bolts: 6293P_P&$prodImageMedium$

Concrete screws: 3839H_P&$prodImageMedium$

Both very sturdy and easy to use. Hole sizes smaller than fixing size.

mullinr2 · 22-11-2017 2:10pm

tooManyChoices wrote: »

You might consider using concrete bolts or concrete screws instead?

Concrete bolts:

Concrete screws:

Both very sturdy and easy to use. Hole sizes smaller than fixing size.

I thought the rawl bolts were the best to use when attaching something heavy to a wall? I'm putting up a pull up bar so it has to carry my weight. Those concrete screws were supplied but only with plastic plugs

tooManyChoices · 22-11-2017 2:26pm

mullinr2 wrote: »

I thought the rawl bolts were the best to use when attaching something heavy to a wall? I'm putting up a pull up bar so it has to carry my weight.

All options are plenty good enough to do what you want. The expansion bolts you mentioned first will hold up a floor.

mullinr2 wrote: »

Those concrete screws were supplied but only with plastic plugs

Then they were regular screws, not concrete screws. Concrete screws are screwed directly into the hole (typically a 6mm hole for a 7.5mm screw)

Anyway, with the expansion bolts you want to drill a hole that just big enough that you can get the untightened expansion bolt into the hole without much trouble.
Have you bought it already? The ones that come with stud&nut would be a bit easier to use as you won't have as much tricking about getting everything just right.

Cerco · 22-11-2017 9:52pm

Check the box. You will often find the recommended drill bit listed.
If not get a calipers and measure the collar. This will give you the bit size.
You can check then to ensure bolt slides in snugly (unexpanded as mentioned above).

DublinDilbert · 22-11-2017 10:45pm

Thunder bolts or brick screws are very good. The problem with rawl bolts is that the hole is very large and the bolt quite small, they also large amounts of stress into the wall.

mullinr2 · 23-11-2017 10:00am

DublinDilbert wrote: »

Thunder bolts or brick screws are very good. The problem with rawl bolts is that the hole is very large and the bolt quite small, they also large amounts of stress into the wall.

Ah here you have me all confused now. Was told by supplier of product that the rawl bolts would be best. Concrete screws were supplied but he recommended using the rawl

tooManyChoices · 23-11-2017 10:14am

mullinr2 wrote: »

Ah here you have me all confused now.

thunder bolts = concrete bolts
brick screws = concrete screws

mullinr2 wrote: »

Was told by supplier of product that the rawl bolts would be best.

They're only comparing expansion bolts to woodscrews/wall plugs, not to the other two options suggested.
Expansion bolts are the strongest, concrete bolts/screws will also be strong enough for the job. If you're ok drilling big holes and paying a bit extra, go for the expansion bolts. if not, go for one of the other option. You've got three options that work here, that's the opposite of a problem.

mullinr2 wrote: »

Concrete screws were supplied...

They definitely weren't.

You were supplied with woodscrews & wall plugs.

mullinr2 · 23-11-2017 10:47am

tooManyChoices wrote: »

thunder bolts = concrete bolts
brick screws = concrete screws

They're only comparing expansion bolts to woodscrews/wall plugs, not to the other two options suggested.
Expansion bolts are the strongest, concrete bolts/screws will also be strong enough for the job. If you're ok drilling big holes and paying a bit extra, go for the expansion bolts. if not, go for one of the other option. You've got three options that work here, that's the opposite of a problem.

They definitely weren't.

You were supplied with woodscrews & wall plugs.

Thanks for your reply. Yea I think I'll stick with the rawl bolts and use a m8. I'll use a 12mil bit first for the expansion bolt. If that's too small I'll use a 14/
No there def concrete screws but for whatever reason they sent plastic plugs.

the_pen_turner · 23-11-2017 11:07am

that's very strange. I have never seen concrete screws supplied with anything.

have you a pic of what thye sent you

mullinr2 · 23-11-2017 11:30am

the_pen_turner wrote: »

that's very strange. I have never seen concrete screws supplied with anything.

have you a pic of what thye sent you

Here is what was sent

mullinr2 · 25-11-2017 7:54pm

I've put up the pull up bar however I have an issue. Two of the bolts won't screw tight. I used a 14mil drill bit and two of the sleeve anchors are drowned in the hole. I can get the anchors out.
Here is my thinking. I used rawl m8 bolts. If I replace the two with m10 this should work?
If I rim the drill bit around the hole to make the m10 fit snug. Such a pain because everything else is fine

the_pen_turner · 25-11-2017 8:40pm

are they sleeve anchors or shied anchors. are they spinning in the hole

mullinr2 · 25-11-2017 9:37pm

the_pen_turner wrote: »

are they sleeve anchors or shied anchors. are they spinning in the hole

Sorry shield anchors. I've managed to take the two out. They just were loose in the hole. The hole was too big. I'll give the m10 a try. My drill can only hold a size 14 drill bit. M10 requires a 16.

the_pen_turner · 25-11-2017 9:45pm

sometimes I have to pre widen then a little or they spin. sometimes I will put them in a wall without the intended bracket, wedge in a bad screwdriver and tighten the bolt then loosen it again (but not pushing back the wedge part) then refit it with the bracket .
I have used silicone to hold them solid in the past if I could wait for it to set

Bruthal · 26-11-2017 6:04pm

mullinr2 wrote: »

Sorry shield anchors. I've managed to take the two out. They just were loose in the hole. The hole was too big. I'll give the m10 a try. My drill can only hold a size 14 drill bit. M10 requires a 16.

The 14 bit should be the right size. They can spin if the shield/sleeve is not held for the initial tightening. Or pre expand it a little by slightly tightening the bolt before they are put in.

I used to prefer the type with threaded rod and nut, than the bolts, but depends on the application.

Bruthal · 26-11-2017 6:08pm

mullinr2 wrote: »

Another question. How are u meant to know if your drilling into the brick or mortar joint between bricks. Is it just pure guess work
TIA

Is it a skimmed brick wall?

You can tell by the feel of it if its the brick or the joints. Morter is much softer than the brick. Larger size drill bits can sometimes jam a little as they go between the blocks in a mortar joint. Smaller ones go in very easy compared to the brick. All of that is much more obvious when you`ve did a lot of drilling into walls.

SixSixSix · 27-11-2017 4:38pm

mullinr2 wrote: »

https://m.youtube.com/watch?v=X9DkX4N9DKU

This is the rawl bolt I'm going to use

In the comments below that video is a reply from Rawlplug:

mullinr2 · 27-11-2017 7:19pm

Pull up bar is up and is sturdy. Now to build massive lats !!

red sean · 27-11-2017 7:22pm

mullinr2 wrote: »

I've put up the pull up bar however I have an issue. Two of the bolts won't screw tight. I used a 14mil drill bit and two of the sleeve anchors are drowned in the hole. I can get the anchors out.
Here is my thinking. I used rawl m8 bolts. If I replace the two with m10 this should work?
If I rim the drill bit around the hole to make the m10 fit snug. Such a pain because everything else is fine

I've used various Rawlbolts countless times over the years with no problems.
Did you measure the dia. of the un-expanded bolt first (as suggested by bonzodog in post#3) to ascertain the correct drill size?
Did you drill a smaller pilot hole first?
It sounds like you went straight in with the big drill bit and the drill was wobbling in your hand with the vibration as you drilled leaving a wider hole than you wanted.

bonzodog2 · 27-11-2017 11:03pm

You could wrap a sleeve of card around the ones that slip

drill size for m8 rawl bolt

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