What’s up with impact energy and SDS hammers? How much of a change in joules/ft-lbs is significant – like are 3j and 3.5j hammers going to be substantially different tools, or do you have to go up to 5, or 6? What can a 15j breaker do that a 10j can’t? Or 20?The size rating is helpful if you’re mostly using it for drilling, but for breaking it’s hard to tell what’s needed as a DIY n00b.Also, are cordless breakers practical for extended use with a couple spares and a charger, or do you really need corded if you’re working for a few hours?
>>2884345It depends on what its for. For removing tiles its better with a smaller hammer, i think thats where the smallest ones are handy. Also smaller ones for removing plaster from all brick walls. Next step would be leca concrete, its very easy to hammer in but lifting a heavy demolition hammer would be tiresome. The bigger/biggest hammers are for real concrete with or without rebar.
>>2884345I've had a Bosch Bulldog for a decade and that little fucker will chew through anything. But if you're demoing a slab you need something bigger. The bulldog will drill into it just fine, but it'll take you forever to break up a slab.So, tool proportional to job size, to answer your question.
>>2884345>Also, are cordless breakers practical for extended useNo, because they're battery powered.
>>2884345>How much of a change in joules/ft-lbs is significantDepends a number of factors, mostly the size of the bit, the weight of the bit, and how hard what you're trying to drill is.As an example, I've got one of the HF rotary hammers, and needed to drill through an 18" concrete wall for some electrical work. It will do a 1" bit no problem. It will do 20" bit no problem. It will NOT do a 1" bit that's 20" long. Too much of the impact energy is dissipated in a bit that long and heavy, not enough is left to break the aggregate. But it just barely chip at it, slowly, with a new bit. Even a relatively small increase of impact energy would make a huge difference there, where you're very close to the bare minimum of what you need for the thing to actually work.At the same time, if you were using a shorter, 1/2" bit, you'd need a significant difference in energy for the drill to be noticeably more effective. Proportionately, much more energy is available to impact the material, and you see a more linear increase in effectiveness with increased energy. At least, up until you get into some absurdity like trying to use a 1/4" bit with a 20ft lb demo hammer.
>>2884345The 3-5J ones you can hold up horizontal or above your head and not murder your arms. The 15J ones are for going down with gravity assist. >batteryConsider that it's a 1500W tool that's mostly constantly using all that power. Consider that a 18V 5Ah battery contains 100Wh. If you have some meme double 40V battery setup, you might get to a whopping 400Wh capacity. That's ~20 minutes runtime. You're also paying out of the ass for the tools and the batteries. Just pull a cord, maybe buy a generator/battery inverter if you need to run in places with no electricity.
>>2884345Stuff like pic rel sucks to do like that, not because of the joules but because you need to hold the drill while kneeling. If you’re just smashing tiles then 10 joules is fine, 15 is nicer for brickwork, if you need to destroy a thick concrete pad then rent a 45j jackhammer instead. If you need to destroy a vertical thick concrete pad, just blow it up or pull it on its side first
>>2884350>>2884365>>2884376I understand tool proportional to job size, but what I’m asking is more about e.g. comparing two tools within a class, one is 4j one is 5j, is that a meaningful difference? Or at the margins of a class, can a 10j hammer do everything a 15j can just more of a pain the ass, or are those actually as incomparable as a little 3j is to the 10j?One practical upshot, I have to demolish a large concrete wall in a situation where running a generator wouldn’t be ideal for some logistics and safety considerations. I have Dewalt and HPT and I’d definitely like to be able to just go with the HPT cordless/corded 36v rotary hammer for this – 11.something joules, does everything even though I don’t need a rotary that big, would just get a breaker like this if they had it. But looking at a selection guide on Hilti’s site, it looks like the *ideal* would be something like the 21j TE-800… so I’m left wondering if I can get away with it with the smaller tool and it’ll just suck a little more, or if it truly needs a larger tool like a corded breaker or e.g. Dewalt’s huge expensive 19j, 2” cordless rotary. If so I might just skip over the 10ish j class, get a big breaker and along with an SDS Plus for drilling… but I might get a larger one with more oomph for chiseling than I would if I also had the relatively handy 1-9/16 HPT 36v.
>>28843944J vs 5J is not a meaningful difference. 10J vs 15J you can probably notice, but I doubt there's anything 15J can do that a 10J explicitly can't.
>>2884394Rent one for a day, take a shot at the wall, bring it back and buy a smaller/larger one as you feel you need. Works much better than asking online and you’d want that before buying a €1900 hilti
>>2884582Thanks.>>2884638Zero chance of me actually buying the Hilti lol, they just have a nifty selection guide for their breakers and I was trying to compare the joule specs of their models to things I can actually afford.
>>2884345I got a 3.2J Metabo Multihammer for small shit around the house. Drilling holes, removing tiles, maybe a narrow slit for a cable, stuff like that.I once broke down a small wall with it, took a bit longer than I would want to, but it did it. Next time I need to get rid of a wall I'll get a 20J demo hammer, but that won't replace the metabo for all the jobs it does well cause it's gonna be 5x the weight and size.You won't notice the difference between 3J and 3.5J, but you notice the difference between 3J from a reputable brand and 5J from china. China joules are shit.The reason I got the 3.2J Metabo is cause that's the largest model they offer which is still a 1 handed tool in a pinch if you're on a ladder or some shit and need to drill a hole in the ceiling to hand some shit overhead. Well that and it's very flexible with the 2 quick change chucks, 2 gears, good torque to also drill with big crowns, holesaws in wood, mixing a bucket of concrete for small jobs, etc.If it's beyond the capability of a cordless drill, it's the tool I grab hence why I tend to recommend it to anyone who has a property to upkeep and is half-way serious about DIY.
>>2884345>for breaking it’s hard to tell what’s needed as a DIY n00b.90lb jackhammer and a sullivan 185 trailer mounted rotary screw. everything else is childs play
>>2886863>90lb jackhammer and a sullivan 185 trailer mounted rotary screw. everything else is childs playBasado. Gave $20 for this old 90# Schramm. Did have to completely disassemble it and clean it up and fix the valve if I remember right. Runs like a dream now. Have a couple Chicago Pneumatic chipping hammers that came with a Leroi 160cfm air compressor I have. It also came with a bunch of bits that fit my 90# jackhammer too! I've only run the Schramm off my 130CFM multi-quip so far...
>>2886879This is Ol' Leeroy when I bought him.
>>2884368>what are spare batteriesI run a cordless compressor forever, just swap a pair of batteries and put the empty ones into the charger. takes like 30 seconds. even if he's in the middle of nowhere with no access to an outlet or a generator, it's just a hammer drill and a couple of spares that he mentioned will last him the whole day
>>2884376>If you have some meme double 40V battery setup, you might get to a whopping 400Wh capacity.40V is a meme currently, no tools, expensive, no 18-20V tools compatibility etc, but 2x18V is perfectly fine with almost all the advantages of 40V and there's a lot of tools like that in almost every popular battery system. I've been buying the 2x18V versions, if available, lately, because the d for certain tools, like circular saws, the performance is basically on par with a corded model that isn't top of the line, with a lot of runtime
