Keyang tools - Demolition hammers - Page 1
Forum section: electronics / general

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 03:17:25 pm
content: Not the best forum for this, I know... But I need to finish my house to get back to soldering!Has anybody had any experience with this South Korean tool manufacturer?I am breaking concrete (light, not reinforced) of the ground floor and their "light" demolition hammers seem to be very nice (right size and power to get into corners etc).However, I cannot find any review for the hammer I'm looking at, despite it being sold since at least 2011 unchanged!http://loventools.com/keyang-5kg-1050w-sds-max-demolition-hammer-kh-5000m.htmlThis is sold for 310€, or about 8 days of renting a tool of similar characteristics.I have about 25 days of works (short term) that would use this hammer.

author: Monkeh
author_rank: Super Contributor
timestamp: June 21, 2017, 04:28:36 pm
content: Even a cheap one is likely to survive your single job.

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 21, 2017, 06:03:21 pm
content: That kind of tool - called an SDS rotary hammer here in the US - is meant for rapidly drilling holes in cement block and that sort of thing, not really for demolition work. You really want to rent a jackhammer to break up a concrete floor - while a rotary hammer might work, it will take far longer and there is a high risk of breaking it (they aren't really intended to be used continuously in the pure hammer mode).

author: Monkeh
author_rank: Super Contributor
timestamp: June 21, 2017, 06:09:31 pm
content: Quote from: MagicSmoker on June 21, 2017, 06:03:21 pmThat is not the kind of tool pictured. That is quite visibly not a drill.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 06:17:55 pm
content: I'm a "buy once" kinda person.I have a whole house to rip, then a brick and mortar garage to destroy, then a workshop to build...I was going to go Makita, but this thing is tempting: much more power than my Metabo rotative hammer, or Makita in the same size range, but stilll light and within budgetFound a vid from the manufacturer: all the internals are metal and it's made to be taken apart, a good sign.A few websites say it is made in South Korea, so that's good too...I think I'll buy and making a review!

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 06:30:31 pm
content: Quote from: MagicSmoker on June 21, 2017, 06:03:21 pmNot a drill, I allready have a SDSPlus Metabo hammer drill.This is an SDSMax light demolition hammer (electro-pneumatic)For breaking foundations, I rent a pneumatic hammer.This for floors (4cm concrete or 6cm light concrete) that I must be carefull with as there are pipes, a cellar and other stuff in the earth below.Or breaking brick walls I can't get frisky with the sledgehammer.I could do it with the Metabo (I have done test trenches for the architect with it) but it would be slow...

author: SeanB
author_rank: Super Contributor
timestamp: June 21, 2017, 06:32:18 pm
content: Just use for the recommended duty cycle, 10 minutes per hour maximum, and it should be fine for the job. If higher duty them plan ahead and get a Bosch rental for a day or so to do the major work, and use the light one for the finishing touches. Having a SDS drill though will be useful to drill into concrete, brick and even stone, it is a lot better than a regular drill for this job, a lot faster and less fatiguing as well.I have a Bosch at work, and a cheap Ryobi one at home, and it is perfect for the work I need it to do, even though I have used them both to drill 55mm cores in concrete, something that they are not really rated to do, as they are rated at 25mm max for a SDS bit, but they are very light, which is handy up a ladder drilling above your head into either a wall or into a ceiling.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 21, 2017, 06:39:22 pm
content: The machine is for light duty demolition. So it might be about right, if you don't have to pay for the time. The corresponding Makita machine would be about twice the price and similar weight.I don't know that brand. Even with a better know brand, there is a chance a machine may fail. With a lesser known brand there is a little more risk for failure, but less financial risk. Form the video is looks good so far, but no picture of the motor or the bearings.

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 21, 2017, 06:40:17 pm
content: Quote from: Monkeh on June 21, 2017, 06:09:31 pmHere is a SDS rotary hammer:Sure looks like what the OP posted, no?And note that most rotary hammers that take SDS bits can operate in hammer-only, drill-only or rotary hammer modes. The pure hammer mode would be selected for demolition, obviously.

author: Monkeh
author_rank: Super Contributor
timestamp: June 21, 2017, 06:51:19 pm
content: Quote from: MagicSmoker on June 21, 2017, 06:40:17 pmSimilar, yes, the same, no. Having experience using all these tools, I can recognise the differences - like lack of space for the gearbox required for it to rotate, and lack of controls to select rotation, hammer rotation, locked hammer, or free hammer..

author: Unknown
author_rank: Unknown
timestamp: June 21, 2017, 07:03:18 pm
content: Quote from: gildasd on June 21, 2017, 03:17:25 pmI have a Bosch demo hammer (which takes sds tool bits) that is somewhat larger than the one pictured. It's great for smaller demo jobs or digging a quick ditch. I assume you're talking about demoing a concrete slab. You might want to rent a similar tool for a day and see if it meets your needs. I wouldn't want to jack an entire slab with mine, though. There are bigger demo hammers for that.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 07:18:14 pm
content: Quote from: MagicSmoker on June 21, 2017, 06:40:17 pmRotary hammers and demo hammers look similar and use the same bits.But having used both, a "pure" demo hammer of a similar wattage of a rotary hammer is lighter, harder hitting and, having less moving parts, hardier.On a purely subjective basis, I found demo hammers to be less tiring, but yeah, subjective.I already have a very good Metabo SDSplus rotary hammer, using it in pure hammer function over extended periods makes it heat up too much. So I'm looking for a demo hammer that uses SDSMax bits (one class above SDSplus) to do that.However, most demo hammers are in the 10kg+ Range, and are both too powerful (approaching pneumatic hammer damage capacity) and too heavy to use on ladders or laterally.

author: vodka
author_rank: Frequent Contributor
timestamp: June 21, 2017, 07:21:16 pm
content: Quote from: steverino on June 21, 2017, 07:03:18 pmSimilar thishttps://picclick.co.uk/Heavy-Duty-1700W-Electric-Demolition-Jack-Hammer-Drill-322212687962.htmlWith this tool chop the concrete as butter

author: rustybronco
author_rank: Contributor
timestamp: June 21, 2017, 07:29:03 pm
content: Have you given thought to renting a masonry saw and an eight Lb/ four Kg sledge hammer?

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 07:38:27 pm
content: Quote from: steverino on June 21, 2017, 07:03:18 pmFor the rebar concrete I rent a pneumatic one that comes with a compressor. But that's overkill for 90% of the work (and very tiring).There are two layers of concrete:- top layer, 6 to 8 cm, light and sandy, could simply smash it to bits, but problems below:- middle layer, compacted earth and broken brick, pipes and electricity pass here, all is supposed to be disconnected and safe, but I've had a few suprises (an African friend, an electrician, came to take a look and said "this is worse than Africa") so I can't go medieval on the layer above.- bottom layer: 4cm of strong, slightly reinforced concrete that is full of quartz pebbles... Cutting it with a diamond disk is a waste of money, so I will weaken the edge flush with the fondations, give a few friendly tapetytaps with a sledge hammer to crack it, then break into smaller pieces with the demo hammer.This house is a real pain in the butt, I need to be touchy-feely with it.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 07:44:08 pm
content: Quote from: vodka on June 21, 2017, 07:21:16 pmYeah, but I would have to explain to the wifey why we need a new ceiling on the cellar, and it's too heavy to carry on the flat roof to break the concrete joists safely.Nice, but overkill.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 07:51:25 pm
content: Quote from: rustybronco on June 21, 2017, 07:29:03 pmI have a masonry saw (a small one), and will be using it to score the top layer into rough squares that I will break/lift out with the demo hammer.I have a 4 kg sledge hammer, I love using it, I've even given it a name: Tappy

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 21, 2017, 08:07:09 pm
content: Quote from: Monkeh on June 21, 2017, 06:51:19 pmAh, yeah, I probably should have clicked on the link to the actual tool - it only operates in hammer mode.That said, it's still a bit light duty for demolishing a concrete floor bigger than a square meter or two. But I also see that the OP said there is a cellar underneath this floor, so it might not be smart to bring in a real jackhammer.The other suggestion by @rustybronco to score the floor with a masonry saw to get get it break up easier is a good one, but makes a real mess unless you use a saw with a water sprayer on it.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 08:11:28 pm
content: The video is a three part job:AndVery nice, but no armature view and no money shot of the reduction gear...However, proper screw connections and a beefy piston.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 08:14:05 pm
content: Quote from: MagicSmoker on June 21, 2017, 08:07:09 pmOr wet the floor as you go, makes the disks last waaaaaay longer!I'll take pictures tomorrow.

author: gildasd
author_rank: Frequent Contributor
timestamp: June 21, 2017, 08:26:22 pm
content: 4 min in: the armature is epoxied, yes!And ALL the bearings are user serviceable! That is pretty neat at this price.The drive sprocket is a bit small, but you can't have everything...However, the rotor is available from the manufacturer as spare part and this company does not seem to change models twice a year, so not a real issue.Ok, I'm buying, thanks for the input!