Valcut and question re depths

[rrrgcy]

Have a trepan job and thought (I thought I thought well) to get the ready-made ValCut (used, though one cutter, haven’t tried it yet). A la Swiss the shaft isn’t .500” but a touch chunky (metric) so need to bore or order a bit and ream a holder to 13.5mm. First time I’ve hit that paper wall. I’ve not ground cutters anything like these. Online images and reading and Penn Tool weren’t helpful (they advised contact the manufacturer, yeah sure, no answer archived terrible cust service), but I’d like to know how the cutters differ to cut differing depths since it’s one way they sell them:

Q. Are greater depth cutters with longer scoops/lips and or increased back rake or the actual cutting angle changed to more vertical off the horizontal (bottom)? How are they different? Has anyone ground HSS cutters (my plan) to follow the profile but how-to for thicker material? I need to do 1/4”-1/2” lo-carb steel. The “sheet steel” cutters look the same as do all the others for thicker. I’m wary to buy a set, whether from France Germany (broken sets) or USA (full 5) and would rather just grind some. These are fairly $$$.

 

[LKeithR]

As the diameter of the hole increases the required clearance decreases. I've hand ground a couple cutters
in the past to cut larger circles. They were single point trepanning tools used in a lathe, not circle cutters
like you've shown, but the principle is the same. I drew the circle full size and eyeballed the tool over it to do a
rough grind and then tweaked the clearances once I started the cut.

Are you doing a bunch of these? Or just a few? And are you planning on using a lathe or a mill? I only ask
because the factory made trepanning tools which use replaceable inserts are a bit pricey but they sure do
work slick...

 

[rrrgcy]

Thank you it’s about the depth I’m interested in, I don’t want to screw up this sole cutter. I was enamored of that “works slick” everyone beams about and those encouraging but very smoke producing videos. For use w mill, 2" dia. discs, a trial Qty dozen, w added ops including inner boring; part sells at about $55 ea.

(I hadn’t thought about it but using the lathe I’d just tail stock chuck it - shaft does have three flats - inspect results and sneak up on the diameter normally, but my Q. still holds on how cutters differ for depth….)

 

[Milland]

Trepanning cutters are tricky, and while I keep one or two around for emergencies, if I have any number of holes (or disks) to make that could use them I'd prefer a proper hole saw like one of these:

Annular Cutters & Rotabroach Bits - Metal - Accessories - Categories

 

[dian]

they are great tools, but good luck with grinding the cutters properly. if you want to use the lathe, just stick the square holder into the toolpost. be carefull, the cutters are not hard to break. all the angles are the same.

 

[CarbideBob]

Only the front tip is cutting.
All else is make sure I do not touch that hole with the side and have increasing clear for chips.

 

[Joe Gwinn]

Have a trepan job and thought (I thought I thought well) to get the ready-made ValCut (used, though one cutter, haven’t tried it yet). A la Swiss the shaft isn’t .500” but a touch chunky (metric) so need to bore or order a bit and ream a holder to 13.5mm. First time I’ve hit that paper wall. I’ve not ground cutters anything like these.

The thing to understand is that these cutters are hooked around the rotation axis so they will cut stably. The principle resembles a gooseneck holder for parting-off and form-cutting tools - as the cutting force increases, the bit retracts a tad, reducing the cutting force, thus preventing a dig-and-break event.

The whole story may be found in the patent cited on the unit, as shown in the picture (see original posting). The patent number is US3470597. Enter this string (including the US part) into Google Advanced Patents and download the pdf.

Online images and reading and Penn Tool weren’t helpful (they advised contact the manufacturer, yeah sure, no answer archived terrible cust service), but I’d like to know how the cutters differ to cut differing depths since it’s one way they sell them:

Penn Tool is a merchant, and knows little of such things. Their Customer Service is focused on sales-related issues.

The French, German, or USA sources mentioned later may be able to help, assuming that they are the manufacturers, not just merchants.

Q. Are greater depth cutters with longer scoops/lips and or increased back rake or the actual cutting angle changed to more vertical off the horizontal (bottom)? How are they different? Has anyone ground HSS cutters (my plan) to follow the profile but how-to for thicker material?

I'd study the patent for this. Also US3468197.

I need to do 1/4”-1/2” lo-carb steel. The “sheet steel” cutters look the same as do all the others for thicker. I’m wary to buy a set, whether from France Germany (broken sets) or USA (full 5) and would rather just grind some. These are fairly $$$.

This thickness of mild steel ought to be OK, but go slow and use lots of cutting oil.

 

[sfriedberg]

Just a couple of comments.

1) I have a few pieces of the two smaller sizes of cutters (width, not depth), and to the eye the geometry on the two sizes is the same except slightly larger. Inside vs outside cutter geometry (e.g., discs vs holes) is basically opposite-handed, with the point and cutting edge sloped the other way.

2) Distribution in the US has been spotty for years, but you might contact Travers Tool as I know they have carried it recently and some years ago they did answer a non-catalog request for Valcut parts positively.

 

[dian]

why not order directly? you even get your companies name on the cutters (see picture above).

 

[CarbideBob]

The deepest I've seen this cutter used is 3-4 inches in steel.
This a special ground bit.
The sheet steel should have a different top hook and lead to minimize burr or push through.
Ideally the radial "twist" changes with diameter along with the clear inside and out.
For sure these can be hand ground out of a HSS blank.
Drawing the cutter tip and slot being cut in CAD can be very helpful even if just 2D.

Also do not be afraid to rotate that drawing to make more sense. People get obsessed with body flat centerline.
The only line that counts is center of the tool to the cutting edge in contact.
Add a flat notch, rad or hook up top and the face rake changes across the tip which you can use to push a chip flow one direction or the other.

I am all in favor of buying HSS chunks, looking at the commercial bought, doing a grind sort of like it and looking at what happen and modifying it.
Be aware that this system usually does not make nice exit holes with standard bits but it certainly does work deeper than you are.
Bob

 

[Joe Gwinn]

why not order directly? you even get your companies name on the cutters (see picture above).

Directly from where?

 

[EmanuelGoldstein]

I am all in favor of buying HSS chunks, looking at the commercial bought, doing a grind sort of like it and looking at what happen and modifying it.

I'm with C-Bob on this, had a real valcut and wasn't that impressed with it. I felt the part that holds the cutter was kind of feasly and the thing liked to chatter. This was in a Gorton using power feed, would be worse in a B'port I bet.

I think you can do better making your own. Or on smaller holes (about 2"), the Hougen Rotabroach things worked pretty good for me. They might work better in large sizes too but I'm too cheap to find out

How big is the hole you want to make ?

p.s. I've gone over 2" deep with homemade face grooving / trepanning tools, so you should def get a 1/2" no problem.

 

[rrrgcy]

Thanks for your thoughtful replies. Considered some Rotabroach some years ago but didn’t buy. Again simple hole 2” dia in 1/4-3/8” thick lo-carb steel. I have plate but geez (to myself, since I’m fixated on flats) yes can do this w using round bar stock lathewise.

I think I’ll work up some drawings and muster HSS grinds and ‘see what happens.’

A bloody fixation isn’t this ?! It’s like exploring anything new and shiny. I’ve realized this is another case where I fall into a trap thinking I just need one more tool (and naturally without a full complement of specific accessories/bits) when I’m focused on plate and I’ve completely disregarded (neglected) other common means like normal lathe trepanning and handground bits. These Valcut cutters just Seem so good with those ‘hooks.’

The year-1969 patent is a little helpful but I’ll rely more on the in-hand cutter. I now see online they’re avail in cobalt and carbide too (about $50 a pop). I presume these are all made in Switzerland, maybe I’m wrong, sellers through only a few spots in USA (and on eBay via France and Germany it seems).

** “The cutting tool 66 is rearwardly inclined with regard to the working direction of rotation, and specifically, at an angle a of to 20, preferably 13 to 17, in other words, the tool is again trailed. Moreover, this groove cutter or tool 66 is likewise provided with a positive cutting angle and is laterally back-slope ground so that it does not rub against the wall of the groove. Under the term positive cutting angle as employed herein there is to be understood that the angle is less than 90, in other words, there is not present any so-called negative cutting edge. The cutting tool preferably exhibits a twist s0 that the groove depth can be selected to be relatively large, without the cutting tool becoming weakened too much in the zone of its clamping location. This cutting tool 66 is fixedly clamped by means of the screw head 77a of the screw 77 threaded into the threaded bore 76. Owing to this construction the cutting tool 66 can be easily exchanged. By virtue of the inclination of this cutting tool 66 there is provided for such a resilient action in that, during the cutting operation, it can deviate or deflect towards the rear, whereby the holder means 65 is subjected to torsion..”

 

[dian]

Directly from where?

from valcut.

op, i think you got it wrong, its rather $50 per 5-pack and might be $30 if you go direct. plain hss, that is.

 

[CarbideBob]

Thanks for your thoughtful replies. Considered some Rotabroach some years ago but didn’t buy.

This a very good tool and made down the street from me.
They stole a couple of my employees and and I stole a couple of theirs.
Even in high school there was sort of a war between the owner's kids of both shops. (That would be me and xxxx)
Difference here is more teeth in the cut and that means faster hole making along with more stability.
Cost more money to make such a cutter but it flies.
Bob

 

[rrrgcy]

…. op, i think you got it wrong, its rather $50 per 5-pack and might be $30 if you go direct. plain hss, that is.

No, it’s $114 -$140 for HSS qty five (5) from Penn Tool. Travers appears to only sell full sets. If you can tell me where to get a Valcut cutter for $10 or less do share (it certainly isn’t 1969 anymore!!). And I can’t imagine Valcut Switzerland sells direct given they have US distributors.

I’ll navigate this Valcut w sheet in the mill then maybe try the lathe… and reconsider a possible Rotabroach if the goods fare well and its value worthwhile for yet a another new shiny tool. Ahem.

(Rotabroach) is a very good tool and made down the street from me. They stole a couple of my employees and and I stole a couple of theirs. Bob

Bob - sneak over and steal a few Cutter Kits (not people) for me.