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IndustryArena Forum > Mechanical Engineering > Mechanical Calculations/Engineering Design > Need help designing a machine to cut timber wood

Thread: Need help designing a machine to cut timber wood

1. Need help designing a machine to cut timber wood

Hi to all, first of all thanks for reading this post. This is my first post in the forum and english is not my first language, so sorry for my multiple gramatical errors.

A bit of history:
I am designing a machine to automate the cut of timber wood (3''x1''x10feet) in 3 pieces. Each piece will have two angles on each end. These type of cuts can be done with a mitre saw, selecting the cut angle and the bevel angle. Attached is an image with the pieces of wood finished. More or less each batch consists on 480 pieces of wood so we need to cut 160 pieces of timber with 6 cuts per piece.

So, my first approach is design a machine that loads the wood into an automated mitre saw (1 stepper to push the timber, 1 stepper to move the mitre saw to the desired angle, 1 stepper to move the mitre saw to the desired bevel angle and 1 linear actuator to pull the mitre saw down once the wood is in position).

The system will also have a 3 limit switches to control the X zero (wood lenght), and the Y and Z (angles) zeros.
Below is a video of a similar machine for the wood length position system that I plan to replicate with the automated mitre saw at the end.

My question is, do you think it is better to have the approach I am going or to build a big CNC and try to make it cut the timber with a proper tool. Both will work eventually but what is the best approach to consume less energy, motors spinning, am I going on the right path?

Thanks of you got to this point for reading this

2. Re: Need help designing a machine to cut timber wood

Hi - If the miter or bevel (depends on how you use your saw) is always 90deg then I suggest you gang the lengths and have more then one saw, Does each batch have different angles and lengths? Plus you need to consider what is called Takt time. ie do you want to do 480 pieces in one day or 1 hour? You will need to develop a few strategies and analyse them. Plus does this need to be scalable? Tomorrow you may need 480 per day but next year you need 3x that then you need an entirely different set up. So the machine needs to be scalable or easy to twin or triple.... and is it to be tended by one person or 2? or unattended full automated? You need to spend a good amount of time formulating the entire problem so the solution chosen is a good one....Peter

https://www.sawinery.net/miter-saw/bevel-vs-miter-cut/

https://en.wikipedia.org/wiki/Takt_time

My observation of the machine in the video is that it will be no faster then a bright person and a mitre saw. The person on a saw will be faster. You still have to have someone load and unload and this is the root issue...

I also see that your parts are stacked in a bench. This means they have to be restacked for transport, this is wasted effort (at your cost) They need to be stacked on a pallet the first time off the cut to minimise motion. Every part motion should be one step closer to delivery vs storage or stacking or parking in some way. Often these production issues are not the cutting process, the cutting time will be the same if the machine does it or a person does it. The wasted time is in transport, set ups, poor process layout, parked product, mismatch between processes, operator overload due to prior mentioned issues requiring part caches or WIP or parking....Think the whole thing through before you do anything...cheers

3. Re: Need help designing a machine to cut timber wood

A saw is the right tool for this job.
If you have the room, multiple miter saws, each with different setups would be by far the fastest method, and probably the cheapest and easiest, if they are setup with quality stops.

4. Re: Need help designing a machine to cut timber wood

You are right in much of your observations. Let me be more precise on what I am trying to achieve.
1) Each batch if 480 cuts (may be more) has 30 different pieces of wood each of them with the same bevel and miter angle on one end and another set of angles on the other end, and of course same lenght, then other 30 with another lenght and different angles on each end.. and so on...
2) I would like to design so we can produce 2 per day and with 1 operator that would load the timber to a stack and prepare the shipment afterwards with the results. If I can start with a 1 per day limit that would be great, but will like to design so I can scalate as you correctly mentioned.
3) Using two saws is the way to as it has also been mentioned by ger21 (thanks as well).
4) the stack would have to be prepared for shipment inmediately after cut and of course avoid unnecesary labour and restacking.
5) regarding loading and unloading I am not certain what would be the way to go... again you are making a good point.. Thanks a lot for your help, I am trying to think well the process before building anything.

5. Re: Need help designing a machine to cut timber wood

Originally Posted by ger21
A saw is the right tool for this job.
If you have the room, multiple miter saws, each with different setups would be by far the fastest method, and probably the cheapest and easiest, if they are setup with quality stops.
Thanks ger21, indeed I agree, will have 2 mitre saws, for each piece of timber, also each have differente angles so it will be easier and faster. Can you recommend me a stop?

6. Re: Need help designing a machine to cut timber wood

Originally Posted by peteeng
My observation of the machine in the video is that it will be no faster then a bright person and a mitre saw. The person on a saw will be faster. You still have to have someone load and unload and this is the root issue...
Yes, that machine may be slower than a good mitre saw operator, one issue is that angles need to be very precise both on bevel and miter. So also having 2 miter saws plus the timber precision measuring, will indeed be much more efficient than the operator..

That also leaves room to improve the loading and unloading (with packaging-pallet stacking) of each piece after being cut... Now I'm also trying to figure out what would be a good decent method to achieve that...