Thread: 45 Degree Cuts with Circular Saw - Brisbane Newbie

There are 4 boxes around 375mm x 224 x 200 and 1 box that is 550mm x 294 x 205

Originally Posted by smal

Hi guys, I'm a bit of a noob but this place seems like a great resource for everything to do with woodworking.

I live in Brisbane and have done a bit of woodworking before, mainly speaker boxes and a little bit of simple furniture here and there. I am building my first set of surround speakers with 45 degree cuts to conceal all of the edges but have limited tools having moved out of home. Do you think a circular saw would be good/accurate enough to achieve a decent result or should I just take it to a cabinet maker?

I'm cutting into a 2400x1200 sheet of 16mm mdf with a Zebrano veneer on one side and a generic veneer on the other. I am using fairly expensive speaker components so I want these to be tidy and would love to hear your thoughts.

I am planning on using a biscuit joiner to stick everything together, looking at getting a cheap Ozito one although I am tempted buy a more expensive Makita one which seems a lot smoother in operation.

Cheers

I believe it is feasible to do clean bevel cuts with a circular saw especially you are using veneer MDF which is fairly level.
Key is a well clamped good straight edge as a guide for the saw's base plate. I often use a ready-cut MDF "door jamb" as guide - door jambs MDF are wide enough for clamping and edge is straight and not expansive. Do not use the rip fence as any slipage will damage the part you want.

Having said that, a saw must have a good (and adjustable=tunable) base plate. And the pivot & lock on the bevel adjustment must be stable. If a cheaper saw can provides that then buy it. Just check before you buy.
Do not trust the scale. Always confirm 45 deg with a good quicksquare or similar.

Is it possible? Yes. Is it easy? Depends on your skills and tools.

All 45^o cuts need to be 45^o. Like wise when cutting across the panel 90^o cuts will need to be accurate. Opposite sides will need to be the same size to have a neat box.

A table saw will enable repeatable cuts more easily.

Good Morning smal

Miter corners must be precisely 45* or the corner will not line up properly. It is extremely difficult to set up a skilsaw (generic term) to cut that accurately.

I have made speaker boxes that way and all the joints were a little out. My solution was to save all saw/sanding dust and use it to thicken epoxy which I then used as a gap filling glue. Thirty years later those speakers still sound good.

A better solution would be to saw slightly oversize and then finish with a router. A lock miter bit in the router would be optimal, IMHO.
Have a look at the Carbitool website.

If you haven't bought the MDF yet, then consider going to thicker stuff than 16mm, especially for the larger woofer box. 25mm is a lot stiffer, and it will improve the sound quality a little.

Fair Winds

Graeme

Originally Posted by smal

Hi guys, I'm a bit of a noob but this place seems like a great resource for everything to do with woodworking.

I live in Brisbane and have done a bit of woodworking before, mainly speaker boxes and a little bit of simple furniture here and there. I am building my first set of surround speakers with 45 degree cuts to conceal all of the edges but have limited tools having moved out of home. Do you think a circular saw would be good/accurate enough to achieve a decent result or should I just take it to a cabinet maker?

I'm cutting into a 2400x1200 sheet of 16mm mdf with a Zebrano veneer on one side and a generic veneer on the other. I am using fairly expensive speaker components so I want these to be tidy and would love to hear your thoughts.

I am planning on using a biscuit joiner to stick everything together, looking at getting a cheap Ozito one although I am tempted buy a more expensive Makita one which seems a lot smoother in operation.

Cheers

accurate 45° mitre cuts will be nearly impossible with a circular saw without spending considerable time and resources turning the saw, building guides and jigs, and finding a FLAT surface to work on -- and even then you could easily be way off 45°

I'd take it to a cabinet maker -- just make sure his panel saw is tuned or you risk wasting your veneer board

How about a 909 Universal Fitment Circular Saw Rail Guide to help if you would want to DIY. Cost just AUD$30 incl.GST
909 is revived GMC. GMC holdings is NOW "globalPowerBrands P/L"
909 is sold by Woolworth's "Masters Home Improvement" - new rival to Bunnings.

Originally Posted by reuelt

How about a 909 Universal Fitment Circular Saw Rail Guide to help if you would want to DIY. Cost just AUD$30 incl.GST
909 is revived GMC. GMC holdings is NOW "globalPowerBrands P/L"
909 is sold by Woolworth's "Masters Home Improvement" - new rival to Bunnings.

Yes the guide will assist greatly (it almost looks like a "Festool" guide). Just remember that is needs to be set up accurately at 90^o to the edges.

Thanks for all the feedback, very helpful.


I do have an ozito router and a 45 degree bit that I got from Bunnings, I didn't even think about using this to do the edges! I'm thinking I might be able to get by with this? I might grab some plain MDF and do some testing. Do you think a lock mitre bit would be better than biscuit joins? I have been following A danish speaker builder who biscuit joins the majority of his boxes. I would have to buy the joiner anyway so I could instead spend that money on some decent lock mitre bits.


That universal rail guide looks quite useful too.


I already have the veneer, I went 16mm as these are just for bookshelf size surround speakers, 1 inch would have made the boxes far more bulky. I have bitumen for the walls and MDM3 wadding for internal dampening. I have 1inch MDF on my 2 front speakers and they are very solid! I made them quite a number of years ago so there is a lot that can be improved, a new set is next on the project list

Good Morning smal

Either a biscuit joiner or a lock mitre will work fine for your job. I have a strong preference for a lock mitre, but that is just me; I seem to get better results. If you haven't used a lock mortise bit before, do a search on the technique involved - there is a little learning, but I think it is worth it.

The 16mm MDF is fine for the smaller surround speakers - hence the qualification in my earlier post.

Gap filling glue will hide any small inaccuracies.

Fair Winds

Graeme