Frequently Asked Questions
Categories
- Diamond Blades
- Diamond Cores
- Cutting & Grinding Discs
- Dust Control
- Safety
- Wire Brushes
- Surface Preparation
- Shaving Systems
1. Diamond Blades
Q. Can I cut any building material with a diamond blade ?
A. Yes, but not with one blade. There are numerous types of diamond blade, each designed to cut different kinds of material. If the right blade is selected there shouldn't be any problems.
Q. Whats the best way to use a dry diamond blade
A. While cutting use a pedelum type motion and bring the blade out of the cut frequently
Q. Should I use a guard with my diamond blade?
A. Yes. Its extremely important to ensure you guard the diamond blade correctly at all times. For dust free cutting use a dust guard.
Q. Can I get a diamond blade to fit any machine ?
A. Yes, the Marcrist range covers all popular cutting machines. Specify the bore required when ordering
Q. Can I use a diamond blade for side grinding as well as cutting ?
A. No, using a diamond blade for side grinding can be extremely dangerous, as the blades are only designed to cope with forces associated with cutting.
Q. Should the diamond blade be mounted in any particular way ?
A. First of all always ensure that the blade is correctly mounted on the cutting machine. When performing the cut ensure that the material being cut is secure, and that the cutting tool is held steady.Gently move the blade back and forth along the cut, ensuring that the blade does not twist. Do not apply excessive pressure to the blade, as it should always be allowed to cut in its own time.This will increase the performance and life of the blade.
Q. Is it better to cut deep or shallow?
A. Shallow cuts result in faster cutting speed and a longer disc life. Deep cutting (single cut) leads to slow cutting speed and a shorter life or possibly to disc overload.
Q. How fast should the feed rate be?
A. Don't push hard, let the blade and the weight of the tool do the work
Q. My diamond blade/core has stopped cutting what can I do
A. First of all check the blade is not worn out. The wearing diamond tip is only on the first few millimeters of the blade. The most probable cause is that the blade has polished (or Glazed) Run the blade a few times through some abrasive material to dress (expose) some new diamonds, alternatively use a diamond dress stone and use the same technique
Q. When should I use a continuous rim blade as opposed to a segmented blade ?
A. Continuous rim blades offer fast and more precise cutting. These blade are a lot more effective when cutting fragile materials such as roof tiles, as the tile is far less likely to break due to the reduced vibrations.
Q. Should the diamond blade be mounted in any particular way ?
A. Yes, the blade should have an arrow on its core (the steel middle of the blade), this arrow should always follow the direction of rotation. If the blade has already been used, this arrow may have worn away.In circumstances like this the direction of rotation may be identified by inspecting the segments. A close look at the diamonds within the segments will show that the diamonds have what resembles a comet tail to one side.The blade should be mounted so that the diamond always leads the comet tail when rotating.
Q. Can I cut circles/radi with a diamond blade?
A. Marcrist have developed special curved blades for achieving this
Q. Blade is twisted after use, what is the cause?
A. There are several possible causes,
Blade being used on misaligned saw.
Blade is excessively hard for the material being cut, creating stress on the steel centre.
Blade improperly mounted on arbor shoulder hence becoming distorted when flanges are tightened.
Blade being used at incorrect RPM.
Material slippage causing blade to twist and become kinked or bent
Q. Why does my blade have more diamond on one side of the blade than the other?
A. The Blade is worn out-of-round due to bad bearings, worn arbor, missing bushing, arbor hole larger than arbor, cleanliness of or damage to flange surfaces or excessive dulling condition.
2. Diamond Cores
Q. Does it matter what speed I run my drill at?
A. Yes, most professional coring drills will display this information on the side of the drill, the speed being dependent on the diameter of the core drill being used. However this is not always the case.The chart link will give the user an appropriate drilling speed for the core drill being used.The smaller the diameter the faster you need to go.
Q. Is there any special technique required to diamond core drilling ?
A. No, core drills are straight forward pieces of equipment to use. In order to start the hole a pilot drill should be used, other wise its just like drilling any other hole. Although a diamond core drill must never be used on hammer action. If the core drill is kept straight and steady, and the core is allowed to drill in its own time (not forced) there shouldn't be any problems.
Q. How fast should the feed rate be?
A. Don't press hard, let the core and the weight of the tool do the work
Q. Can I drill any material with a Marcrist diamond core ?
A. Any material can be drilled with a Marcrist wet diamond core, but dry diamond drilling does have its limitations. Extremely hard materials cannot always be drilled dry, this is because the segments can start to overheat.But this problem can be overcome by using a combi unit to to feed water into the hole to keep the segments cool.
Q. Will a Marcrist diamond core fit onto my drill ?
A. Yes, Marcrist stock a complete range of adaptors to allow our core drills to be used on any drilling machine.
Q. How deep can I drill with a diamond core ?
A. Diamond core drills can drill to great depths by adding extension rods between the core and the drill motor.
Q. The material I am drilling needs to be drilled wet, but I cant have water flowing everywhere. Is this possible ?
A. Yes, the amount of escaping water can be limited by using a water collection ring, these vary in size from 120mm diameter to 305mm diameter. And can be connected to a vacuum system or drian into a recepticle depending on the application.
Q. What are the benefits of buying a diamond core ?
A. The traditional methods of creating a round hole in a wall are extremely untidy, and usually require the operator to "make good" the hole on the side of the breakthrough.This is not the case with a diamond core as they produce a clean hole every time. Using a diamond core also dramatically reduces the time required to make the hole, reducing labour costs.
Q. When wet drilling, how much water should I use ?
A. The flow of the water should be adjusted until the water resurfacing has a "milky" consistancy. This "paste" not only cools the segments down, but also acts as an extra abrasive to help the core drill cut.
Q. Will I be able to drill reinforced concrete ?
A. Yes, but it is important to maintain a constant drill motor speed. When the steel is encountered reduce the feed pressure until the steel has been cleared.
Q. How can I remove a jammed core bit ?
A. First of all remove the drill motor from the core. Take a piece of threaded bar that matches the internal thread of the core drill and place two hex nuts on the rod and lock them against each other.Thread the bar through the top of the core drill and turn via the hex nuts. This will now push the core drill out of the hole without damaging it.
Q. Where can i see some operating instructions for dry diamond drilling
A. The 'How to' data sheet can be downloaded here from a PDF file.
3. Cutting & Grinding Discs
Q. Will metal cutting discs cut stainless steel?.
A. Yes, although in most cases not as well as specialist stainless cutting discs, they will still cut adequately.
Q. Can an abrasive disc be used wet?.
A. An often stated safety instruction is that abrasive discs should not be allowed to come into contact with liquids as this destroys the bonding of the disc. However it is not the liquid itself that causes the damage - but the drying out process, hence abrasive discs can be used wet, but should then be removed and thrown away no matter how much of the disc remains.
Q. On my abrasive disc it says A30 TBF, what does this mean?.
A. This is the technical specification of the disc. The first letter (A) refers to the material specification of the disc, in this case aluminium oxide which is for metal cutting and grinding discs. The number after that (30) refers to the grit size, which in this case is medium sized. The next letter (T) refers to the hardness in this case the disc is hard. The next letter (B) indicates that the disc is resinoid bonded (the gluing agent), and the final letter (F) indicates that the disc is fibreglass reinforced. There are many different specifications of disc, a full explanation of all types can be found within the Abrasive Revolution catalogue.
Q. What safety standards should I be looking for on abrasive discs?
A. With the demise of the DSA, DSA markings on abrasive discs no longer have any significance. Two key markings are EN12413, and VBG 49, it is advisable when using an abrasive disc that you ensure the disc contains at least one of these standards.
Q. I have a 7" inch grinder, but I need to make cuts deeper than the usable radius of a 7" metal cutting disc will allow, as the 7" grinder is identical in dimensions to a 9" grinder can I modify my grinder with a 9" guard and use 9" discs on it?.
A. No. This is one of the most common abuses of abrasive discs. Although the 7 & 9" grinder look almost identical, the 7" version operates at a far higher speed. If you fit a 9" disc on to a 7" grinder the disc will run far faster than the rated 80m/s of the disc, and this is extremely dangerous.
Q. Can I use a cutting disc for grinding?.
A. No. Grinding discs, apart from being thicker are also manufactured using three layers of fibreless reinforcement rather than two. By grinding with a cutting disc you remove the reinforcement from one side of the disc altogether, and frequently chunks of the disc will begin to break off.
Q. Why do abrasive discs nearly always have a red band through the middle?.
A. This signifies that the maximum operating speed of the disc is 80 metres per second, another common band colour is green, which signifies a maximum operating speed of 100 metres per second.
Q. Why do abrasive discs have to be used within 2 years of manufacture?.
A. Abrasive discs are perishable in nature. Although after two years the disc will not look any different, after about this period of time the bond of the disc (i.e. the glue that holds it together) begins to break down.
Q. Is a depressed centre cutting disc stronger than a flat cutting disc?.
A. Not necessarily. The two different types have continued to exist because of personal preference, there are advantages of one type over the other but these are not related to the strength or safety of the products.
Q. I frequently use a cutting disc with an angle grinder, do I legally need to be trained?.
A. It depends on whether you undertake this task professionally. If the grinder usage is DIY you do not need to be trained, if however you undertake this professionally it is the responsibility of the employer to ensure you are trained to a competent level.
Q. What discs can i use to cut Aluminium?
A. You can use Stone discs to cut Aluminium
4. Dust Control
Q. How can I reduce the air polution when contamination is not acceptable ?
A. The dust given off when drilling can easily be controlled by using a combi unit partNo 320.101.0050, this is simply connected to a dust control unit which vacuums the dust away before it can leave the hole.
Q. Can I use an ordinary vacuum cleaner for dust control?
A. When using dust extraction for concrete and brick dust ordinary vacuums cleaners filtesr block up very quickly. This reduces efficency and can ruin the vacuum quickly. Only use machines specifically designed for the purpose.
5. Safety
Q. Can I wear safety spectacles rather than goggles for protection whilst using an angle grinder?
A. No safety spectacles are only suitable for protecting against impacts of 45m/s, as an angle grinder generally operates at 80m/s the protection is not sufficient. The lower protection factor from spectacles is not necessarily due to the strength of the lens, goggles generally offer higher protection because they have the advantage of an elastic band holding them to the head, which prevents them being dislodged by any impact.
Q. I have always used a nuisance mask for respiratory protection when drilling masonry, there appear to be a whole range of different standards of mask, am I alright to continue with the nuisance mask?.
A. In a word no. Nuisance masks offer no protection whatsoever other than keeping large particles of dirt out of the mouth. Always select a mask that is certified to EN 149, and select the relevant standard (FFP 1(S), FFP 2(S), or FFP 3(S)) of mask. These three masks offer different levels of protection, effectively the higher the number the smaller the size of particle the mask will allow to pass though, hence the higher the protection. A formula for determining the level of protection required from any particular material can be found in a safety booklet from the Health & safety Executive (EH40).
Q. Is there any legislation that requires me to wear gloves when using a power tool?.
A. No, it simply makes sense to do so. There are no safety standards with regard to general rigger gloves, but in the case of an accident at least they may afford some protection, however minimal.
Q. When should I wear ear defenders or ear plugs?.
A. Anyone exposed to noise greater than 85dBA should wear some for of ear protection.
6. Wire Brushes
Q. Why are some high tensile steel wire crimped brushed brass coated, whilst others are bare high tensile steel?.
A. Brass coated brushes have two advantages. First the brass coating makes the individual wires more flexible so that they are less prone to breakage. Secondly the brass coating is rust resistant, and hence ensures that if the brush is held in storage for a long time no rust build-up will occur on the wires.
Q. I have recently purchased a wire brush, the diameter is clear but it has no markings on it at all, is it safe to use?.
A. No. The 1986 Power Driven Industrial Brushes regulations state that all brushes must be marked with certain information, one vital piece is the maximum operating speed of the brush, without this information you are not able to determine whether the rated speed is high enough for your angle grinder.
Q. Why did cup brushes come in both twist knot and crimped wire types?.
A. The crimped wire type brush is for light surface cleaning and preparation, whilst the twist know type is far more rigid, not as flexible, and hence far more aggressive.
7. Surface Preparation
Q. Where can I find the Technical Specification for the FR200 range of machines
A. Drill down to the part number for the machine you are interested in then click on Technical Spec. A PDF document will be opened which you can read on-line or print off. A PDF document for the FR200 range is available here.(Click here for more information)
8. Shaving Systems
Q. What is concrete shaving?
A. Concrete shaving is a system designed and developed by Marcrist specifically for nuclear decommisioning work worldwide. See the Special Projects area for more details.