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CNC Celtic Fireplace Engravings

Updated: Jan 24

We were asked by a local fireplace manufacture if we could produce a range of Celtic engraved legs, centre pieces and shoulder blocks for a new style of fireplace surround they wanted to make.

The Meeting

We meet with the owner and production manager and ran through what they were wanting to do, they had seen a similar design elsewhere and had a number of pictures of the components they wanted to make, they asked me if i could help to manufacture these parts I said that was not a problem and agreed to start on them right away as time is always critical in our job.

The designing of the Components

To able to CNC Cut these components on one of our 3 CNC routers we first need to create a CAD file this is a vector file i.e a line drawing like a sketch but something a computer can read. To create this vector Cad file we need to trace around the image the fireplace guys gave us,

Sorting the CAD File

Pretty simply really we scanned the images the supplier gave us and imported them into our design software (we use composer for this ) once we have the images in our software here comes the hard part we have to manually trace around the design to create the vector lines this takes quite a bit of time and has to be accurately done as this is what the cnc machine will follow once we start cutting the material so it is critical that this is done right, after we trace around the design and check all the vectors also making sure everything is to scale only when we are happy do we save it as the finished Cad file.

The real art here is know what type of material you are cutting how you intend to cut that material and what you need to achieve from the CNC machine to get the absolute best quality in terms of surface finish from the cutting, you always want to get the best finish possible from the CNC router as this will minimise any other hand finishing and it's very possible to get a really good finish of the router that requires no extra sanding or clean-up work that's the real difference from a good CNC service provider to a sub-standard one, it is all about reducing that extra work for the next person that's where our 22 years of experience comes into play, we know how things will come out when designing components from machining and this is critical as a bad design will not machine right no matter what you do so starting with a good core design is essential so thats why you want to use Trade Made for any of your CNC Router work .

How we have the CAD file created for all the components its time to start the programing of the CNC. To do this we need to create tool paths I have explained this is previous blogs so check that out but in short we import the the CAD file into another software package and start to set the job up for machining,

The main Legs.

We started with the main legs of the fireplace all material where free issued by the fireplace company so we just had to machine them, the legs where given to us in their finished size so all we had to do was align the blanks in the correct position on the cnc router and machine the main design

one problem with finished size blanks is that we need to be perfect with your machine alignment if you are out by even .2mm it will be noticeable so set up is critical just a quick note.

The way we do this is machine a square datum point on the router and align the blanks to this this means we have a perfect machined point from where the router will cut , once we have a good set up we load the cnc machine with as many blanks as possible again making sure everything is square, accurate and most importantly we have a good work hold down so the blanks do not move when being cut.

How we have our machine set up it time to start cutting with these legs we have only 2 main tool paths (the commands the router follows) an engrave command and a clear out command.

The Engrave Command

The engrave command is the main Celtic design you see where the lines cross each other, this is a very simply command all it really does is send the machine cutter onto the centre of the vector file that you have designed it does have a lot of limitations but it is very handy for complex vector designs like this Celtic weave where there is a lot crossed vectors, before we apply the engrave command we need to set some variables like tool type, machine feeds and speeds and depths etc before you can do this you need know and understand the material you are going to cut as you wrong tool or wrong speed etc. can cause a bad quality job so this is where experience comes in, the material here is pine which does cause a lot of issues if not machined right as its very easy to chip plus it has a lot of resin in the wood which makes machining small detail hard so attention to the correct tooling and speed is critical, we use a special tool for this engraving and basically cut the design twice once for a roughing pass and a second pass for the final smoothing of the design, now the engraving command is ready we need to apply the clear out command.

The clear out command

The clear out command is the border you see around the Celtic weave on the outside all this does is cut out an area between to set vector lines in this encase it just creating a design border we used a ogre tool here to give the border a nice round step look this in turn helps make the Celtic design stand out more and I think the fireplace company used this for staining as well when doing the finish work .

Finally time for CNC cutting

Now we have everything ready Cad file check, machine set up check, tool paths ready check, now its cutting time we send the code to the CNC router double check everything again once happy we hit start, the cnc goes and pick up the engraving tool which we have already set up and starts to cut the Celtic design on all the components once the engrave command has finished it replaces that tool and picks up the next one for the clear out command again the CNC router goes and cuts the components once its finished the clear out command it replaces that tool and goes to its home position ready for the next job. We turn off the vacuum hold down system and remove the parts check everything again once happy we set up the next set and repeat. Once all the legs where cut we move onto the centre panels

The Center panels

The center panels where very similar to the legs but with these we had to profile cut the outside shape to give them that arc look.

First of all we remove the previous set up as these panels where to be cut from large planks that was supplied to us so set up was really easy for them, all we had to do was measure each blank and lay them out on the computer this did need to be super accurate as we were cutting the final profile anyway we just had to make sure they fitted inside the planks.

We loaded a couple of planks onto the cnc router bed and made sure they were right on the computer software, the problem with real wood and a lot of sheet material is they are normally wrapped or curved some way we see this all the time, with these planks we had to add some screws to keep them flat on the machine bed as the vacuum pressure could not bend out the stress of the natural curve in the planks it's not a big deal we see this a lot with natural woods especially in long wide pieces, how the planks where set up and ready for cutting we had to add the tool paths for machining we used the same tool paths as we did for the legs but with difference variables like cut depth and speeds the only extra commands we used was the profile command which cuts the outside shape, once all command where applied and checked we started the machining there is some trade secrets in cutting pine as cutting it wrong is very easy to do and can make a mess of it very quickly so if you need pine wood cnc routered come to cutting edge design that's if you want it done right, anyway once cut there were removed and the next set up done.

The Center Rose Panel

The Rose centre panel was a totally different panel as it was 3d carved, this type of machining takes a long time to do and I will go through this type of work in a different blog as its hard to explain it all but essentially it can machine any type of 3d design as you can see from the picture it is really nice but too expensive for a basic fireplace surround, it took 6 hours to machine just this one panel which is not cost effective for a semi- low budget surround

The final parts where the shoulders

The last bits to cut where what I called the shoulders that's probably not the right name buts that's what I called them anyway they were basically the same as the other parts they had the 3 commands on them the only thing was the manufacture wanted us to profile around the final shape but leave them in the planks i.e not cut the full way through as they said they were going to trim them of after they came from us maybe easier for them to painted them not sure why but that's what they wanted, anyway that was fine we done all the cnc work and left them a couple of millimetres left to trim off when they got them back.

We made hundreds of each part and different variations of design but unfortunately the fireplace company these where for closed which was a shame as we enjoyed making these engraving, so if you need any CNC Routered Celtic designs or any wood engravings simply give us a call or email what you would like done we have the experience and knowhow to do get it done

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