PDA

View Full Version : DIY Insert Holder (pics)



Ryobiguy
01-17-2010, 04:43 AM
Here are some pics of a 5/8 shank TPG 32x holder that I made today.
Yes it's ugly, but it gets the job done, which for me isn't very demanding.
Figured I'd show it anyways since it's fun to see photos of little projects!

The insert only sits against one shoulder.
I was considering trimming down one of the sides flush to the side of insert, and bolting on a second shoulder to get the insert to repeat.

On the mill I eyeballed the compound vice to the appropriate angle to cut the shoulder, and then tilted the spindle over by 7 degrees to give it positive back rake and positive side rake, equal for both turning and facing. Hopefully that leaves sufficient relief with the 11 degree TPG.

I was considering making the top clamp come a little closer to the cutting edge, and grinding a concave radius chip breaker on it. Not sure if that would work, but for now I have gotten it done just enough to test it out.

I haven't turned with inserts before, so I'm amazed at how much material it can tear off at high speeds without breaking a sweat.

-Matt

http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/01top.jpg

http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/02overall.jpg

http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/03clamp1.jpg

http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/03clamp2.jpg

John Stevenson
01-17-2010, 05:48 AM
Second picture, may I respectfully suggest you drill and knock in a pin to the left of the insert to stop the insert moving up the taper.

If it does slide up under aggressive cuts it will deepen the cut, making the cut more aggressive and probably ruining the job.

Nice starter job BTW, thanks for showing it.

.

j king
01-17-2010, 05:49 AM
It needs a back shoulder to keep insert from pushing back. It looks like you made the seat with a positive angle and that makes the clearance at the tip almost nil from the looks.The leading face should be cleared out and angled with clearance below the cutting edge.The way it is now you couldn't take anything more than a fuzz cut. Just constructive criticism.

Ryobiguy
01-28-2010, 03:50 AM
OK, after I got past the fascination of being able to use the carbide insert, I went back and redid some of this.

I changed the back/side rake angle to +5 degrees from +7 which was maybe a bit too steep.

I cleaned up the shape of it, following the silhouette of the bottom of the insert, and added extra clearance angle on the front (still need to do that to the side.)
That was the first time I used my new pair of right angle blocks to do some compound angles. Kind of fun.

Then I added a front shoulder - kind of a fiddly design but it works. John's idea of knocking in a pin for shoulder would have been a bit simpler.

I still need to make a new clamp that uses a chipbreaker.

http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/newTopView.jpg

http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/frontShoulder.jpg

Note the clamp block area is parallel to the plane of the insert:
http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/withoutInsert.jpg

Reflection from cutting tip on 1-2-3 block's surface, showing rake, relief, and clearance from the screw:
http://img.photobucket.com/albums/v129/Ryobiguy/TpgHolder/rakeAndRelief.jpg

-Matt

Black_Moons
01-28-2010, 04:05 AM
Very awsome looking holder.
I have seen commerical holders that actualy take a little 'plate' inbeween the carbide insert and clamp that acts as a chip braker, so your idea of a chip braker in the clamp could indeed work.

I like the side clamp part too, On my 'commericaly' made cheapo holders (uses tapered screw, no clamp), I can sometimes see the insert rotate ever so slightly in the holder when taking cuts, but I think thats more because the hole/support ledges are in the slightly wrong location. your side clamp part might kinda get in the way of some operations near shoulders.

One thing I notice is on your clamp, the support to the toolholder is RIGHT next to screw, this is a lever remember, so I believe having the support to the toolholder about the same distance as the support to the carbide would provide more clamping force.

Ryobiguy
01-28-2010, 04:39 AM
Very awsome looking holder.
I have seen commerical holders that actualy take a little 'plate' inbeween the carbide insert and clamp that acts as a chip braker, so your idea of a chip braker in the clamp could indeed work.

Thanks!
Hey look what I found, ANSI standard for carbide chipbreakers on clamp type tools: http://www.ccpa.org/pdf/B212_20.pdf
I've got a gemstone faceting machine with diamond laps, and I think I could make one of these.
I've got some smaller harbor freight inserts, think they would make a good chip breaker, or would they perform just as poorly in that role?


One thing I notice is on your clamp, the support to the toolholder is RIGHT next to screw, this is a lever remember, so I believe having the support to the toolholder about the same distance as the support to the carbide would provide more clamping force.

Yes, you're right. I was thinking of filing down the clamping surface of the clamp so it's a bit more of a wedge shape. But eventually I'll probably move the clamp's ledge back and make a new clamp that's bigger so the screw is closer to being in the middle.

-Matt

Black_Moons
01-28-2010, 04:59 AM
I think it might also be that the point of the clamp is to prevent rotation/movement, And you just need 2 ledges for 'indexing' the insert against.
iv seen some holders that only have a tiny nub to support the 2nd edge.
How about the 2nd ledge being on the left side? comming in from behind the insert.

the pin (and clamp) inserts would only need one edge to index against.. and then be rotated against it (to maintain a consistant indexing position, nothings perfict)

You could also just buy the chipbrakers from the same places you buy your inserts. a few diffrent holders iirc have them, just buy one and modify it to fit under your clamp.

Please continue the expairments so I stop looking at those $100+ insert holders and make my own :P

And hey don't get discouraged by people who say 'it won't manage to cut anything deeply'
The tiny little screw that holds most of the carbide inserts on my tools scares me.. yet they take 0.1" deep cuts in steel at 0.01" feed rates (And spue scalding hot chips clear across the shop if I dare run the SFM high enough) without failing.

I do kinda wonder about some of the more professional holders though

Like, do they have a relief to match the insert relief on the support ledges? (tapered endmill?) (I assume the ledge is shorter then the insert to prevent pressing against the cutting edge itself)
Are the pin (and clamp) type really designed to hold the insert against the ledges firmly? do they actualy have the pin hole mil or two too close to hold it firmly or do they have it +- tenths exactly to just rest the insert against the ledge

j king
01-28-2010, 06:43 PM
That looks much better. I made one years ago and welded the rear support instead of a screw. That will work fine now.

darryl
01-28-2010, 09:01 PM
Looking at your third picture, the top clamp 'heel' is touching the holder at a point near the bolt. If you machined that bottom area of the clamp such that only the back edge of the heel is touching down, you'll get about double the clamping force on the insert for the same torque on the bolt.

danlb
01-30-2010, 10:19 PM
Nicely done. I've thought about making some extra holders for my lathe. Thanks for the inspiration.

Dan

featherhead
02-02-2010, 01:12 PM
Let me add my "nicely done" to the thread. Next question, are you doing this part in tool steel so it can be heat treated? Assuming 5/8 thickness it may hold up to cutting forces, but it has to hold up over time. So I'd keep an eye on it to make sure it's not deforming.

dp
02-02-2010, 01:33 PM
Conga rats on your post becoming an HSM Talk article!

http://email.villagepress.com/pub/HSM/Newsletter/20100127/20100127.htm

Carld
02-02-2010, 01:47 PM
Ryobiguy, one thing to consider is the angle of attack the leading edge will have. If the holder is at a right angle to the work then the insert will be at an obtuse angle to the axis of the work and will tend to pull the cutter into the work. That is not good and will cause an under size cut. To be an effective holder it should hold the insert at a right angle or less to the axis of the work.

I doubt you will have much deformation of the holder if it is not hardened. I have been using a home made holder of CR steel with a triangle insert in a flycutter for years and have seen little if any deformation of the pocket and I take cuts that some consider very heavy if not impossible with no trouble at all on my mill.

JoeLee
02-02-2010, 02:58 PM
Would have been easier to just buy a Valenite tool holder for about $30. I've paid even less for some of them brand new.

JL......................

mello1
02-02-2010, 04:25 PM
A tip for you guys Most of the catalogs for valanite and the other makers of holder have tech drawings of their holders which will help in establishing the proper geometry for your holders. also they sell clamps and separate pieces which have been heat treated etc. you don't want to be penny wise and dollar foolish scrapping several hours of work over a 2.00 clamp.

glenco2
02-14-2010, 04:23 PM
You could make an eccentric stop held down with an allen screw that would let you adjust the position of the stop.
Glen