Advice needed on sanding small items for production

[niall Y]

Just a thought from an outsider with no experience with CNC but what sort of cut would you get from a PCD bit - at least for taking off that final whisker. I know they are expensive, but could you somehow get to see an example of your material cut with such a bit. Maybe a firm like Scott & Sargent would be able to advise on the suitability.?

 

[mwinfrance]

What would be the major product of CNC and wood? Is it used on an industrial scale at all?

IME..Phone covers and similitat stuff out of PRC.

 

[J-G]

Just a thought from an outsider with no experience with CNC but what sort of cut would you get from a PCD bit - at least for taking off that final whisker. I know they are expensive, but could you somehow get to see an example of your material cut with such a bit. Maybe a firm like Scott & Sargent would be able to advise on the suitability.?

Never even considered PCD bits - I use mostly solid Carbide - up to 3mm - or Carbide Tipped above that. I do also use simple HSS Milling cutters on occasion, with comensurate reduction in speed.

My 'final whisker' cuts are often sub 0.1mm

 

[worn thumbs]

What would be the major product of CNC and wood? Is it used on an industrial scale at all?

I'm actually a bit surprised to see this being asked.I think we can reasonably assume that most modern kitchen cabinets are produced on various forms of CNC machinery.It can also be a revelation to see some of the 3D objects that can be created.I will add some links to videos that demonstrate some aspect of what can be achieved.
This one is basic V carving,rather similar to the example I posted earlier and I would have included a G04 early in each sequence to allow the spindle to reach operating speed before beginning the cuts :

This is a general introduction to hobby size machines :
Some 3D carving :

Making a handrail sweep on a 5 axis machine:

Carving a 3D figure :

All of which is taking us away from the query at the head of this thread.I am tempted to suggest looking into vibratory finishing,but don't know a great deal about it.

 

[mwinfrance]

I am tempted to suggest looking into vibratory finishing,but don't know a great deal about it.

be very careful when googling such phrases.

 

[Ollie78]

Thanks Ollie & sorry for the super delayed reply.

Yes similarly mine is cutting at around 2.5metres a minute feed rate with spindle speed 18k rpm. I've been using 6mm straight bit as I don't need the bottom face to cut cleanly and I'm a bit nervous of using a compression bit on this thick 25mm poplar - do you find the compression bit gives you a cleaner cut all the way through compared to straight / downcut bits or is the main improvement the clean front & back faces?

I'm using climb cutting as found that got the cleanest results but i can see that the areas that fuzzies are left seem to be where the router is travelling in the same direction as the grain on Poplar.

Since I made this thread I've tried using birch ply and can get that really clean cut with no finishing which is brilliant but i prefer aesthetically the poplar so I'm still keen to figure it out. I'm going to order a couple of high quality 6mm bits to test on the poplar to see if i can get a cleaner finish - do you have any favourite bits you'd recommend?

Thanks, Natalie

The compression bits give a very clean cut in everything I have tried, the spiralling of the cutting edges means the cuts are shearing the fibres more that chiselling them at 90 degrees if that makes sense.
If your not so concerned about the finish on one face then a spiral up or spiral down (depending on which face matters most) will also produce better results than a straight 2 flute. The chips are a noticably different shape with spiral bits, they seem much less likely to build up friction in the cut and burn as well, though good extraction is still important.
Rennie tools do some nice bits at fair prices, Scott and Sargeant do the CMT range including the solid carbide stuff and often have deals on them, very nice quality.
The stuff from no name Chinese manufacturers on Amazon and Ebay is a bit hit and miss.

Ollie

 

[HowdyMurph]

The compression bits give a very clean cut in everything I have tried, the spiralling of the cutting edges means the cuts are shearing the fibres more that chiselling them at 90 degrees if that makes sense.
If your not so concerned about the finish on one face then a spiral up or spiral down (depending on which face matters most) will also produce better results than a straight 2 flute. The chips are a noticably different shape with spiral bits, they seem much less likely to build up friction in the cut and burn as well, though good extraction is still important.
Rennie tools do some nice bits at fair prices, Scott and Sargeant do the CMT range including the solid carbide stuff and often have deals on them, very nice quality.
The stuff from no name Chinese manufacturers on Amazon and Ebay is a bit hit and miss.

Ollie

Thanks for this Ollie I've tried running a separate finish pass with a downcut bit to take off a last 0.8mm and whilst it is a better finish the straight bit alone it still isn't completely smooth enough to be able to skip the sanding and jump straight to waxing. I'll try running a separate finishing path with a compression bit today and see if that's any better. Frustrating because on tests with birch ply i can CNC, then lathe and then wax immediately so it's miles more efficient - i just don't like the way it looks for this project as much as the pesky poplar!

Yeah I've got most of my bits from Rennie tools and just V bits from Amana. I've not heard of Scott & Sargeant I'll have a look at them!

Thanks, Natalie

 

[HowdyMurph]

Thanks for the

Just a thought from an outsider with no experience with CNC but what sort of cut would you get from a PCD bit - at least for taking off that final whisker. I know they are expensive, but could you somehow get to see an example of your material cut with such a bit. Maybe a firm like Scott & Sargent would be able to advise on the suitability.?

Thanks for this suggestion. I spoke to someone at Scott & Sargeant this morning and they advised PCD bit would be more suited to harder materials. The Poplar is very soft and carbide should be ideal - like @Ollie78 they suggested an up / down compression bit for the cleanest cut even when i don't need the both faces to be clean! Off to try that now...