Tersa knives

[memzey]

Hi everyone.

I wondered what users of the Tersa system made of the different metals the knives come in and where most people buy theirs from? Is there an appreciable difference in quality of finish and/or longevity that comes with the different alloys and brands of maker available? Or is it all marketing and they are all basically the same?

 

[Adam9453]

I buy mine from hammer and I did pay the extra for the longer lasting knives, can't remember what the actual metal is though sorry.
Seemed expensive for disposable knives when I bought them but they produce a superb finish and they're lasting well so I'm happy with them.
What machine do you have?

 

[marcros]

i got mine from woodford tooling. I asked a similar question a while ago, when i first got my machine. The consensus was to go for the m42, so I did. I have no other tersa ones to compare them with.

 

[ColeyS1]

i got mine from woodford tooling. I asked a similar question a while ago, when i first got my machine. The consensus was to go for the m42, so I did. I have no other tersa ones to compare them with.

I tried normal hss before m42. Hss was rubbish in comparison. I found the cheapest place to source them was via ebay [WINKING FACE]

Coley

 

[marcros]

I may be telling you wrong. It may be via Appleby woodturning that I got mine and I think it was also via eBay.

 

[memzey]

i got mine from woodford tooling. I asked a similar question a while ago, when i first got my machine. The consensus was to go for the m42, so I did. I have no other tersa ones to compare them with.

I tried normal hss before m42. Hss was rubbish in comparison. I found the cheapest place to source them was via ebay [WINKING FACE]

Coley

What was rubbishy about the hss in comparison if you don't mind me asking? Did they not produce as good a finish or did they go off too quickly? Or both maybe? :duno:

 

[ColeyS1]

They didn't seem to keep a good edge very long. Admittedly I mostly use hardwood so perhaps it might be less noticeable using softwood

Coley

 

[marcros]

IIRC when I researched, hss were recommended for softwood, M42 for hardwood and the carbide for professional use. The carbide were megabucks, and the professionals tended to prefer to switch blades out (which takes about 2 mins) than risk hitting something and ruining an expensive blade.

With tersa, it is so quick to change them out, you can (and may as well) have a set that are used for literally the final pass only and saved for best. when the normal ones need changing, you put the best set on, and have the brand new ones saved for the final pass.

 

[PAC1]

One of the advantages of the Tersa system is you can and should have a variety of blades and swap them around as needed and make sure you always have new set or spare edge for finishing. Accordingly you can decide for yourself if the M42 make a difference or whether to stick with HSS.
I have got my blades from Appleby, they will give advice as to which are best for each circumstance.

 

[memzey]

Thanks that all makes sense. Reading a bit more it seems that the HSS knives have a keener edge and give a slightly better finish than the M42s but the M42s edge lasts a lot longer. Sounds like the best way to do it would be to leave the M42s in the block until the final finish pass then swap them out for the HSS. It barely takes a minute to swap out all four knives so shouldn't be a pain - as long as I haven't lost the nail punch and hammer!

 

[Stuart]

I buy mine from Thames Valley Saw Co. and I can recommend their service and helpfulness.

 

[ScottandSargeant]

HC is high chrome content in black and orange packet... Ok for soft woods. And supplied as standard in blocks when you get the machine
HSS is HSS In green and orange pack .. Ok for mixed hard and softwoods... Most popular choice
M42 is almost same as HSS but has slightly more obtuse cutting angle, works well on oak, more expensive
Then there is also Solid carbide available in different grades...
There are also some copy versions around since the patent expired.... Some good, some poor

The Solid carbide can be reground but you will lose about 0.1 mm on cutting circle

 

[OwenRS]

I second the above. Tersa's advantage is its versatility and there is no such thing as one knife suits all. Pick correctly from the above and it will out perform all other finishing heads out there.

Been linked with Tersa for almost 20 years now and they still won't confirm the grade of the HSS. Copies are good but don't come close to Genuines unique grades. To put a few questions to rest the Genuine M+ as it's now known (originally branded M42) is exactly the same high grade Material as the standard HSS. It just has the bespoke grinding off the carbide knives. Gives approx 30% longer life in hardwoods but not as good in softwoods.

 

[memzey]

That's interesting Jeremy, thank you. You say Tersa with the right knife will outperform all other head types; do you include the spiral types in that analysis as well? Is your estimation based on time/cost/quality of finish?

 

[OwenRS]

Well great question actually. Lots of pro's and lots of con's.

2 types of spiral heads. Both using Carbide tips. Compared to a Tersa HSS head and obviously it will last longer Spiral heads use carbide tips. Will it give a cleaner edge no. In short HSS is a very stable material and can be ground to a razer sharp edge giving a beautiful slice through your timber. Carbide as a norm is hard wearing but brittle hence the backed up thicker cutting angle. Combine the thicker edge and the hard wearing material it last longer.

The two spiral heads are normally a roughing head with 30 to 50mm tips (Tersa will never be a roughing head) and the second would be a finishing head that uses either 14mm, 15mm or 17mm tips. Great heads but please do not believe if you have 140 tips in the block if one gets a chip you reverse just the one. You have to remember 140 tips now have wear and the one your rotating with be larger and potentially leave a step in the finished edge. To combat this the 3 sizes of square tips come with a large radius edged (eg R=150mm) to fool the human eye that can not see a slight radius to radius overlap.

Cost to cost Tersa wins hands down due to time to change a single knife and also the fact one block can do carbide and HSS which spirals can't.

 

[memzey]

That's brilliant Jeremy, thank you so much for your insight. My machine has a 4 knife block, spins at 4,000 rpm with a 4" cutting radius and gives such a nice finish using the hss knives that the wood gleams. I had read some mixed reviews about the spiral blocks, some saying they were very good, particularly on figured wood and others that they were problematic. Your post seems to clear that up nicely, thanks again.

 

[PAC1]

Another advantage with the Tersa is that when planing difficult grain you can quickly change the blade to a new edge when you have 1 or 2mm to go and approach the finished size in steps of 0.25mm or less. With care a very good finish can be achieved with minimal tear out. Whilst you can do the same with the tips on the spiral head, time and finish are factors.

 

[OwenRS]

TERSA Money Saving Tip No.1

Although Tersa is a Super Super high tolerance knife location system it will still only give a single knife finish. Meaning one knife will be sticking out of the block a microscopic amount more than the others and it will be this knife that is leaving the finish on your wood. The other knives will be pre relieving the depth of cut the finishing knife takes.

SO..... if you have a 4 knife block please do not think if you want to run the HSS, M+ or the Solid Carbide knives you have to have 4 of them. Try using lets say 2 of the M+ and 2 of the budget grade Chrome knives. Stagger two of the Chrome opposite to each other and do the same with the M+ in the remaining slots and you will save approx 30-35% on the cost of the two Chrome Knives.

IF by chance, a Chrome knife is the one sticking out as the finishing knife it will soon wear back and the M+ knives will take over your finish cuts. This can be achieved replacing the M+ knives for HSS with approx 25% saving and also on the Carbide knives approx savings 90%. Saving you Money on a system thats already saving you time.

Be clever with Tersa and I stand by comments that Tersa is the most versatile system money can buy, no other system has the range of knives in one block.

Keep viewing for more Money Saving Tersa Tips.

 

[memzey]

Alright I'm subscribed for the next exciting episode!

 

[OwenRS]

Who's got a wide Tersa block but never uses the full width?