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This question is a kind follow up to this other question. Indeed, now that I know how to glue pieces of mugs, I'd like to know how to cut them. The idea is to get some cheap IKEA mugs with various colors such as this one:
IKEA cup
Then I'd like to cut them into pieces (preferably not too many, say 3) so that I can reassemble them (by gluing the pieces). The goal is obviously to stick mug pieces of different colors together. For example, the cut should be along the red lines of one of the picture below:
enter image description here enter image description here enter image description here

I'm open for other cutting lines if it makes the process easier. I'm also open to consider a different type of mugs but should say that minimizing the price is important as I potentially would like to make several of them.

My question: Is cutting a mug as above possible and if yes, how?

  • Normally you'd cut ceramics with a wet tile saw, a band saw, or something similar, however most of these wouldn't have a long enough cutting edge to cut a mug (and opening up a bandsaw wide enough to cut a mug could cause it to be too unstable for the job). – Tom Medley May 31 '16 at 11:30
  • @TomMedley Thanks for your comment. Does it implies that such a task is impossible for a nonprofessional? – Surb May 31 '16 at 12:29
  • I'm not an expert, nor do I have much experience cutting ceramics in general, hence I haven't made this into an actual answer. I doubt it's impossible, but you'd almost certainly need some quite specialist tools I imagine. – Tom Medley May 31 '16 at 12:56
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    Is the end result to be decorative or functional? Could you not just paint it instead :). Perhaps you would try mugs with more complicated textures? – Matt May 31 '16 at 16:08
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    @ChrisH see the linked question in the OP. – Surb Jun 1 '16 at 12:27
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A grit edged hacksaw blade (random example) would be the hand tool for the job. It would be a bit of a slow job but not unreasonable (given the rate these things go through tiles).

I suggest making/modifying a jig based on a mitre box to go with it, if you want repeatable, straight cuts. The jig itself might be a bit tricky as it sounds like you want straight, repeatable cuts. You should be able to cast modelling clay, plaster (or even hot glue) around a mug to around half depth using cooking oil as a mould release, all inside a home made or cheap mitre box. Then clamping the workpiece down would be a good idea.

Like with power tools, work wet. Unlike power tools you need frequent (rather than continuous) water delivery -- though the latter would do no harm.

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Forward

While this answer might seem long it is unfortunately not as in depth as I want. I have not cut any ceramics with the tools and techniques I am going to suggest. Given the desired end result I feel that this would be an approach to consider though.

This might be difficult depending on your level of expected precision and tool availability

I have a suggestion but it involves tools that could be expensive to acquire and potentially a difficult process (I have thoughts on that as well near the bottom). The cuts you propose and the shape of your mugs will affect this as well.

Consider wet tools

When it comes to cutting materials like glass or ceramics with power tools, wet tools are always advised. You don't want these material fragments stuck to your cutting instruments. Nor do you want the inside of the machine to be exposed to them. Aside from hand tools, that would not have this issue, I would suggest that any power tool you consider be a wet tool.

Easy tools to comes by for this type of task would be a wet tile saw or a ring saw. Both are for cutting ceramics and glass (as well as some other materials). However neither common variety will have the thickness clearance of your average mug.

Therefore a wet band-saw would be a good suggestion here. While there are not too many of these available from what I could tell the real issue is trying to get precision cuts with one of these devices. Of the 4 common ones that showed up in my research they had mostly plastic frames (Likely due to the use of water) and only a couple had what I might consider a mitre slot (Which would be useful for making custom bandsaw sleds). This is important part of the precision I think you would need.

Mitre Slot

Note: The above picture is not a wet bandsaw. It is used to highlight the presence of a mitre slot.

Consider the following related video where a bottle is cut with a wet bandsaw

Jigs

The problem with mugs is, depending on your cuts, you cannot make them perfectly straight free hand. At least not without practice experience. This is a major factor here since you intend to reassemble them after. This is also a hard topic to expand on as every mug and every style of cut might need a specialized jig.

Consider the features of this jig\sled on a bandsaw.

mitre sled

The wood in the picture is being held against two fences. Rear fence holds the work 90 degrees to the blade and the other fence is adjustable (see the wheel) to help move the cut in or away from the blade.

Your cups are not flat (at least not the one pictured) so you will need to modify this design. When cutting into curves you need to prevent the cup from rolling around so an easy way to get that is to have two blocks angled into each other (like chucks on a car or plane wheel).

enter image description here

Made in sketchup to illustrate the design

Cup has somewhere to rest and the adjustable fence will give you something to push against to make sure the cut is straight. That design only covers your first cut examples though.

Getting mugs of a uniform width makes this part so much easier to mitigate. A jig would be useful if you were using power tools or not. The idea is to place the cut in a certain position where it will not move unpredictably while you are cutting it. If you are doing it with hand tools then clamps would help as well. Clamps would be good for power tools as well but their position could be awkward and you don't want to risk damage.

Blade kerf

Regardless of your cutting tool, powered or not, you are going to have an issue with the kerf(width of the cut) of blade. Let say that you cut the mug down the exact middle of two identical mugs. Lets assume that your blade kerf is 1/8". When you go to put that mug together it will now be ~1/8" smaller so the edges of the mugs won't line up.

Not the end of the world obviously. You can address this but cutting off center on your mugs. On one mug you could cut a kerfs width to the right of the cut line and the other a kerfs width to the left. This also means you could have to cuts extra mugs to get the pieces you need. This also assumes your level of perfection your are trying to achieve.

When you are cutting make sure you cut slow. Make sure you cut slow as to not force the blade askew or cause any burning.

Conclusion

I think it is doable with power tools but unless I am way off the mark there would be some work involved in getting the right environment to do this properly . If you are willing to concede on some degree of perfection and willing to practice I think hand tools might be the way to go like Chris H suggests. Several caveats above would still apply. You might, in either case, consider food safe grout to make up for any size consistencies.

It is still feasible though how I describe.


Access to tools/workspace

There are locations that are set up for you to have access to industrial tools. So if purchasing them outright is not in the budget or you are just curious to test; look for something like this in your area.

TechShop is one of these public workshops that, with a membership, gives you access to tools and work space. They have locations all across the United States (which is obviously not useful for all). There are other places like this that exist for the purpose of tool rental and tutorials beyond what you would get from something like a big box store. TechShop is just an example.

  • Thank you very much for this nicely detailed answer. So, I'll definitely try the technique of Chris first (cheaper and I believe that hand-tools are somewhat safer for a nonprofessional). I'll check if there some workshops around where I live (not in the US though). The video showing how to cut a glass bottle is also very inspiring (looks like it is possible to make some nice drinking glasses out of old wine bottle :). – Surb Jun 3 '16 at 16:04
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    @Surb You're welcome of course. Don't forget when you are cutting them by hand my warnings about the cutting width of you tool! When it comes to wine bottles don't forget about these options as well. – Matt Jun 3 '16 at 16:09

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