tersa system

[marcros]

How does the tersa blade system work?

By that I mean, do I need a specific block on the planer, or do you convert the existing one?

Are any models more or less suitable for the system- I am thinking for my next planer or planer thicknesser. Much as I like the idea of the spiral block, there is a good argument for having a set of blades just for the last pass through, given that the Tersa are supposed to be self setting and quick to change.

 

[RogerS]

My understanding is that you need a special block.

Depending on your planer/thicknesser you might like to have a look at Barke Turnblades.

 

[deema]

I have a Sedgwick CP p/t with a Tersa block on it. I love the system, you can literally change a blade in less than a minute. The blades simply slide in and through centripetal force lock into position. To remove you tap on a bar that holds the knives in place and pull them out. There is no setting or checking heights. The blades are reversible rather like an electric hand planer.

The Tersa block can be bought as a separate unit to upgrade a P/T, there are usually some new ones on eBay. If you upgrade a machine you will need to reset the height of the outfeed table, the pressure and feed roller for the Thicknesser. If you have a nice vintage machine, this isn't too difficult. Some modern machines don't allow you tho make the adjustment required. You have to reset the heights to accommodate the new cutting circle of the Tersa block, but once it's done, you will probably only need to check the outfeed table height / orientation to the infeed table once a year just in case any bolts etc have vibrated loose / the tables have moved due to being repositioned and bedded in.

You can also upgrade to a spiral block instead, same applies. Last time I looked there about the same price. For me, and it's very much a personal thing, I do not like the thought of swapping the spiral head cutters. The propect of loosing the small screw and then getting the new cutter seated again when the block has been used and has resin where you would least like it fills me with dread.

 

[marcros]

The thing that attracts me to the tersa is the speedy change which makes having a couple of sets of blades on the go at a time a possibility. The spiral seems to have some advantages but replacing all of the cutters when they need it sounds like a large undertaking. Still not fully decided.

The Sedgwick is on my list, and somewhere near the top of it at present. I would prefer a standalone planer but to make upgrading the block pay, I would have to go for a pt. I want something that I don't need to upgrade (ever) again.

 

[marcros]

If a planer has blades with a funny self setting profile to them, does this suggest that they may be tersa? It was an option on the model I am looking at, but seller has no idea. They are certainly disposable ones

 

[marcros]

Damn, missed it!

 

[heimlaga]

I would never do such an upgrade. Having to buy new knives every time they get dull becomes a lot of money in a 50 year perspective. Furthermore it isn't very likely that all manufecturer specific knives will be avaiable forever.
Therefore I prefere an ordinary gibbed cutterhead with normal straight HSS knives. They may not produce the best result nor be the easiest to set but they are cheap to resharpen and when they wear out I can get a new set. I recently bought two new sets of knives for my 1957 model Stenberg KEV 600. Standard knives from Edessö. No problem. They weren't even expensive. I don't think it will be that easy to get all models of speciality knives 50 years from now.

Just my oppinion......

 

[doctor Bob]

I would never do such an upgrade. Having to buy new knives every time they get dull becomes a lot of money in a 50 year perspective. Furthermore it isn't very likely that all manufecturer specific knives will be avaiable forever.
Therefore I prefere an ordinary gibbed cutterhead with normal straight HSS knives. They may not produce the best result nor be the easiest to set but they are cheap to resharpen and when they wear out I can get a new set. I recently bought two new sets of knives for my 1957 model Stenberg KEV 600. Standard knives from Edessö. No problem. They weren't even expensive. I don't think it will be that easy to get all models of speciality knives 50 years from now.

Just my oppinion......

Tersa is widely available, been around for years, this is not an issue.
On a commercial basis time is money, tersa is fantastic.

 

[deema]

I use genuine Tersa M42 knives, which at c£13 each is really good value I think. I need 4 on the Sedgwick, which makes the total cost for a set £52. However, I get two sides to each knife, so this is the cost of two sets of knives when comparing to standard knives. I.e £26 a set. On my old planner which had standard knives it cost c£25 to get a set sharpened. I did not do them myself as I felt that getting the knives even slightly out of balance (different weights) caused vibration / poor surface finish + dangerous!. With standard knives you should really have three sets, one on the machine, one at the sharpeners and one spare set. A good set of knives used to cost me c £50~£60 a set. So three sets was £150 to £180 investment.

I find the M42 knives last at least twice as long as standard HSS knives so in truth I believe I would have to go through about 300 sets of Tersa knives before the Tersa system cost me more than standard knives. That's a lot of planning!

Of you have anyone working for you, Tersa has another advantage. You can be confident that your employee will have put the knives in correctly and they won't fly out.

 

[heimlaga]

Then Tersa is the best solution for you though it isn't for me.

To me joinery is a side income to carpentry. The turnaround is pretty small which makes it important to keep the investment costs down. I always have occasional spells of underemployment which means wasted time from a strictly economical point of wiew. I try to make use of those spells for tool and machinery maintainance. The cost of a tersa cutterhead would pay many hours of knife setting for me.
In a bigger business everything I do would not be economically worthwile as the manager is generally busy full time and all machinery maintainance has to be paid at a full hourly rate including taxes and insurances and all.

 

[doctor Bob]

I always have occasional spells of underemployment which means wasted time from a strictly economical point of wiew. I try to make use of those spells for tool and machinery maintainance.

Interesting, whats your strategy for ensuring your blades will be blunt or chipped only during quiet spells?

 

[heimlaga]

They aren't....... according to Murphy's law. Though one or two hours of fixing in midst of a project usually just postpones the project with one or two hours making the next quiet spell one or two hours shorter.

Setting two 610mm long knives using a wooden stick as guide takes one and a half hour or so. As the work is done for myself and hence not taxed the lost income is only my netto income after all taxes and fees as they are proportional to the money I earn. I will do it at lest 130 times before I have paid for a 2000 euro Tersa head.

It all depends on your own personal situation......

 

[PAC1]

I do not do enough to justify changing the cutter head of itself but having bought a machine with a Tersa head I would not now dream of using any other. The speed of change and the time saving not having to faff around lining the blades up makes it worthwhile let alone the fact that a set of blades cost the same as sharpening the alternative. Overall the Tersa system is a very economic system if you specify it on the machine at the time of purchase

 

[marcros]

Well, I am happy to say that at long last, I have bought myself a Tersa- blocked Inca machine, which I am planning to collect at the weekend.

What is the thoughts on knives- there seem to be chrome, HSS, M42 and Carbide widely available.

Woodworking is a hobby, so I am not planing all day every day. I typically use native timbers- my current stock is lacewood, oak, cherry, walnut, elm and yew (and will likely be replaced with a similar selection when used) if that is a consideration. I would probably have a set as final finishing knives, and swap them out for the last pass.

 

[ColeyS1]

Well done on the purchase, looks like a little beauty I originally bought hss and was very unimpressed- the m42's seemed to hold a edge much longer. I'd recommend a white board marker for scrawling when you've 'fitted new blades' and 'changed blades' on the side of the machine. It's quite interesting to see roughly how long they last

Sent from my GT-I9300 using Tapatalk

 

[marcros]

Doesn't she just!

When you say that you weren't impressed with HSS, was it the longevity of the edge or the finish.

 

[deema]

If your cutting hardwoods such as oak go for the M42 blades. The HSS give a better finish, however they don't last as long. Oak is particularly aggressive in blade life. The cost difference isn't that much and the genuine Tersa blades are excellent. I would not buy an alternative brand as they don't seem to last as long. I buy mine from Woodford, they also sell on eBay. IMO you normally would not go from P/T to finishing and some form if surface clean up is always necessary regardless of blade type. The M42 is again IMO the best value blades for all applications

 

[ColeyS1]

The finish was fine, just didn't stay that way for long, not compared to the old hss blades in previous planer.

Sent from my GT-I9300 using Tapatalk

 

[marcros]

If your cutting hardwoods such as oak go for the M42 blades. The HSS give a better finish, however they don't last as long. Oak is particularly aggressive in blade life. The cost difference isn't that much and the genuine Tersa blades are excellent. I would not buy an alternative brand as they don't seem to last as long. I buy mine from Woodford, they also sell on eBay. IMO you normally would not go from P/T to finishing and some form if surface clean up is always necessary regardless of blade type. The M42 is again IMO the best value blades for all applications

I bought some blades a little while ago on ebay- they were genuine tersa, from woodford. I fitted them the other night and the finish was like glass on some elm. it has quickly deteriorated from that though, with a relatively short amount of use. I am certain that I ordered the m42 blades, but they are not marked, so I couldnt be certain that that is what was sent. Is this to be expected- i have only planed up a half dozen or so boards, and they are coming out ok, but only ok?

 

[deema]

The blades will have the Tersa logo and name plus the grade of blade stamped on them. If in doubt give Woidward a call. They are extremely helpful and knowledgable.

The finish will deteriorate from a glass finish fairly rapidly, as with all things, running at the speed they do the finest of edges dulls a little faily quickly. However, what is important is the amount of power or effort that you require to push the boards through. I can only describe it as you 'know' when they are too dull because the effort to push through increases significantly and the finish falls off rapidly. The tone of the machine changes and sounds far more laboured.

Dirty timber will dull blades very quickly as will taking off large amounts off at once.