So, to cut a long story short, I'm going to install some 12mm rebar as stakes for kerb setout. A couple of them will need to be in a concrete slab, so I'm going to have a crack with a 18V Makita cordless hammer drill, with a 12mm hammer bit. The photo below shows at lower a 14mm hammer bit, and the 12mm hammer bit at top, i.e. the ends that go in the drill. The 12mm has a nice point on it, and I have visions of it hammering its way into the internals of the drill, so should I grind it flat?
I see the 14mm with the flat end says non hammer only, so maybe not.
Since it is just for curb stakes, wouldn't a drill hole or cross cut be a lot easier?
Ken
I would not grind that point flat.
But it sure seems like overkill. Is there a risk of impalement should someone trip and fall onto one?
?ÿ
The stakes are 300mm offset from back of kerb and will have 100mm above top of kerb marked on them.
SDS cordless drill will cope with a 12mm hole a lot better.
The point may help the hammer stay centered in its bore.?ÿ I have about a dozen Bosch hammer bits, but I've never noticed a point.?ÿ They're buried deep in a temporary storage shed at the moment, so I'm not in a good position to check.
The point is simply the difference between manufacturing styles.
I like the SDS style of bits or the ones that have a rounded triangular shape for the shaft that attaches to the drill.
The polished round fittings are harder for the drill to make a grip and usually spin and not dig into hard things like rock and concrete.
I use a DeWalt DC212 18v-20v rock drill with a 5/8in and 3/4in bit with an SDS connection. It is slotted and will not allow the bit to spin and will go thru concrete and rock very well.
My favorite thing is to locate a rod under the surface of a road with my Schonstedt and use the rock drill and a 3/4in bit to quickly find it.
Can also use an adapter to put a regular keyless drill chuck and use regular bits and garden augers.
Well, today being Sunday was the day to do it as the kerb construction work will start on Monday. Didn't do it yesterday (Saturday) as the likelihood of drunks et al destroying things would have been very high. Took note of the advice above and didn't grind that tit off (unlike my front tooth - re the dentist, which is another story). She whistled thorough the concrete like the proverbial, and although I didn't check, I couldn't detect any damage to the drill. Set five stakes in concrete.
Other stakes were just hammered into the pavement aggregate, and a few of them were problematic as the sub basecourse is cement stabilised and I couldn't hammer the rebar through that - contrary to the above, the rebar I got was 10mm, which is too flimsy for heavy bashing, and in hindsight would have been better with 16mm or 20mm to smash into that layer. Got nervous at the thought of buried electricity.
For the bars in concrete I started off with that epoxy. But probably symptomatic of them being direct import from the East, and cheap at the supermarket, the tubes were 75% air by volume (hope the manufacturer had a good laugh), so ran out at bar two. Set other bars with superglue.
Horiz position was with RTK, sweet. A few minutes after the first two photos were taken, things got more emotional with rain, thunder and lightning, which I didn't see coming as I was in between buildings - we'd normally pack the base/radio in such conditions, but too far away to do that, luckily didn't get hit. Persevered, knowing RPLSToday expecting a result. Tomorrow we'll auto level them to tape-mark the elevation.?ÿ
BTW, I do have a SDS chuck adapater for that drill, but concluded some time ago that it needs mods to work. Can't remember why at the moment.
I'm a little late to this, but for future reference -
1. I use an 18v hammer drill also. If I have to drill larger diameter hole I first drill out a 1/4" hole, then 3/8", then 1/2", etc. The 1/4" hole takes the longest, reaming it out progressively larger goes quick. Easier on the drill and chuck.
2. Perhaps this business of setting stakes at a specific vertical offset is a local thing for you. Here, I would have set mag nails at ground level and given a cut/fill to the curb/kerb top for each.
3. There are specific bits made for hammer drilling purposes. Using any other type for that job, modified or otherwise, is a loser.
4. SDS chucks and bits are the way to go if you are doing lots of hammer drilling.
5. 1/2" (#4/13mm) rebar is the smallest I'd use for staking.
6. When needed, I use this epoxy putty for setting monuments. But the thing I worry about dislodging my monuments is frost heave. Those bars aren't coming out of those holes without considerable effort, with or without glue.
I suspect the constant vertical offset is so they can set up a string to follow with the kerb slip forming machine. Otherwise they have to set up their own pins from your nails. Which is possible but he subbie may prefer the surveyor to do it to avoid mishaps.?ÿ
Here's what the contractor has done with the setout stakes (red flagging, and white tape marks). The stakes are 300mm beyond the back of kerb and the white tape marks are 100mm above top of kerb. They have run a rebar "stringline" 100mm down, i.e. at the top of kerb level. I guess the reason why they used rebar and not string, was so that they could bend the rebar to the shape of the roundabout. The 300m offset is so that the stakes wont be in the work area. They'll build the kerb then set everything else off that.
?ÿ
Indeed. That's how a curb machine works. But if the contractor believes that having you do this for him is economical you are not charging half enough.
They have their own surveyor, but occasionally, as in this case, he's out of town for a few days on other jobs so they get us in. Maybe, though, on their internal accounting sheet, his charge out rate is the same as ours.
Mostly, the contractors wanted the actual Back of Curb staked and they would do the forms and/or offsets for curb machine themselves and we did not have to worry about staking anything except the actual locations which were part of the plans.
Wow, this seems above and beyond.?ÿ Out here we'd probably just give them some scribes and PK nails and let them figure out how to string it up.
Here's what went down (there's a prize in there for the keen-of-eye):
Having to squint and turn my head sideways to see but, aren't some of your red-topped rebar, at the 300mm o/s, and the others right at the bc ?
?ÿ
ok, wait, not all of them are red-topped.
Horizontal offset?
The curb seems to be precast sections rather than the more common poured in place. Not a problem, except I can't see whats going to hold that portion of the curb that sits on top of the sidewalk in place. Also the existing asphalt - such as it is - needs to be sawcut so that the patch can have a chance of lasting.?ÿ?ÿ
