Way to hold/center round stock ???

[joa]

I'm routing and engraving oak "hubs" that I cut out with a hole saw. They are 3.25" wide. I need a way to precisely hold them. Something like a flat 3-jaw chuck that will fit under the gantry. Anybody know of such a creature made for woodworking (actually a 3-jaw vise) that's relatively affordable (don't need an expensive metalworking one IOW)???

Thanks for your suggestions!

Joa

[matticai]

Joa,

Machinists sometimes make soft jaws for mill vises out of aluminum to precisely hold uniquely shaped (in this case 'round') workpieces for mill work. Replace the hard jaws in a vise with jaws made from spoiler material, cut the profile and go. It's important to clamp down on something before you cut your profile otherwise the loose jaw will flop around.

Matt

[rgbrown@itexas.net]

Joa,

I built a "clamping ring" to hold some round parts I worked on once. I simply cut a circle with the ShopBot, cut a slot in the circle where it could 'contract' and used a blot and nut to hold the part while I machined the parts.

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[rgengrave@aol.com]

Joa if you had T-Track on your table you would be able to hold any shape.

Ron V

[bill.young]

Hi Joa,

How about something like this:
392

The part on the left would be stationary and fastened to your ShopBot table, and the part on the right would move to clamp the disks, maybe by clamping the two blocks together or with some push-pull toggle clamps.

It would be ShopBot-able, could be made to hold as many disks as you want, and would be easily replaced if it got chewed up.

Bill

[gerald_d]

Just to go back to step 1 for a minute; Must you really cut the blanks first? Maybe you could machine everything else and then use the SB to cut the circles last. But, of course you have already thought about this.


I just want to break the typical mindset that one must cut out blanks first at all costs.

[joa]

Hey guys, great suggestions, thanks! Good picture too Bill! Actually, that's almost exactly what I'm using now (a diamond) but for some reason the bugger just isn't wanting to center real well (partly because the part that slides isn't real tight I think plus the pieces are a little rough and not quite the exact same shape, IOW have a flat or rough spot on them so don't center). Plus I have to flip the piece over and the other side is rounded (edges) and hard to hold. Hard to describe but in a nutshell I've tried it and simple hold-downs are fine for a few pieces but for the production work I'm doing I think a centering vise is the quicker way to go.

I have also tried milling the pieces out of flat stock rather than using a hole saw and it works but takes a lot longer and wears my bits (thick Oak) plus I have to flip them over to do the back side anyway so need some way to hold them after they're cut.

Since I posted this I've been searching the web and may have answered my own question this morning. I found that Harbor Freight has a 4-jaw wood lathe chuck that will hold up to 6" for $20. I think this is the way to go here.

Thanks again for all your suggestions guys and I'll let you know how the HF chuck works in case you're ever doing something round.

Joa

[rgbrown@itexas.net]

Joa,

The HF "4-Jaw wood-turning chuck" is a POS.

I will try and post pictures of my 'adapted' 3- Jaw chuck this evening. It is on a lathe but the principles are the same - center the piece and hold.

[gerald_d]

A 4-jaw chuck is generally NOT self-centering. If your blanks are uneven, then you will soon tire of setting up 4 screws every time you want to hold one piece.

From your description, it sounds like you need the more expensive SELF-CENTERING, 3-JAW chucks where tightening one screw always gives a centered result. You might be able to borrow or hire one from a metalworking friend.

[rgbrown@itexas.net]

Joa,

Here is my 3-jaw chuck turning a steering wheel. The jaw pads are customized to the part. As they are wood, I just make new ones when I need to.




Ron Brown - rgbrown@itexas.net

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[rgbrown@itexas.net]

try teaux
\image

[rgbrown@itexas.net]

try trey

393

[davidallen]

if you're using a hole saw, does it use a centering drill? if so, how about a coarse thread screw mounted on the worktop?

if the circumference is out of round, can you really center the disk from the perimeter?

da

[beacon14]

How about routing the back first, without cutting out the blank, then flipping the blank over, routing the face, and finally cutting out the shape last? Depending on the piece, it may be easier to register on something that has been routed out of the first side than trying to position the round part perfectly from the outside. I hope this made sense, it's very clear in my head!
Another thought, since your parts are only 3 1/4", you could start with 24" boards and do 6 parts from each. Then you would be able to register the board on a straight fence, flip it over and use the same fence. You would only need to register the end properly. You could use tabs to hold the discs when through cutting.

[gerald_d]

David JB, your description makes complete sense, but Joa already said; "I have also tried milling the pieces out of flat stock rather than using a hole saw and it works but takes a lot longer and wears my bits (thick Oak) plus I have to flip them over to do the back side anyway so need some way to hold them after they're cut."
(I could imagine what quality you would get after hole sawing through thick oak and this is not pretty. That is why I think a 4-jaw chuck will make things worse - not better. But it all depends on how much accuracy you are really looking for.)

We pretty much do 95% of our work with 1/4" cutters and have never even considered hole sawing to reduce wastage or time. I have this funny feeling that a 1/2" cutter will push you into Joa's way of thinking (load small blanks into the SB), while a 1/4" cutter will send you into David JB's (and our) way of thinking (load boards into the SB)?

[beacon14]

Gerald,
I understood Joa's post, but I thought it was worth putting out the idea anyway. If Joa can't (or won't) use it, maybe someone else can.

I think your comment on the bit diameter may be quite relevant. I was amazed at the Jamboree when Bill P. told me he cut 1" MDF with a 1/8", 1 degree tapered bit in one pass at 1 1/2ips. I have ordered 2 of them to try it for myself.

[billp]

David, I hope I didn't mis-speak at the Jamboree; the bit is 1-1/2"long, and I did the cut at 1 ips.I'd set your "Z"plunge to about .75 as well so you don't torture the bit on the initial plunge..Using those speeds I was able to cut 17 sheets of 1" thick MDF in a single pass with only one broken bit ( because I trapped a piece of loose material under the dust collection brush and it tried to plunge through two inches of MDF at once..).The unfortunate remedy for that was to remove the dust collector, and eat MDF for the next two months..Bill P.

[garbob]

Hi Bill,

Can you please provide more detail about these bits such as manufacturer and distributor, cost, etc. They sound perfect for mdf.

Gary

[billp]

Gary.Ron, et.al., I learned about the bit from Chris Burns at Shopbot. I bought it from MSC;1-800-645-7270, their part # 02958023. It is a 1-1/2 ", 3 flute, carbide, ball nose end mill with a 1 degree taper, and a 1/4"shank. It costs about $35 , but with UPS,tax, etc, about $44 to my door. Chris had said that Shopbot will also be selling an identical bit, so you might start to nag them for info..I have also used their 2"version, but it's HSS, yet for my 3D work in foam it's all I need. That part # is 97875330-2",3 flute,3/8"shank, ball nose as well. $40, to the door-$50. If you live near an MSC you can probably pick them up...

[ron_cleaver]

MSC also has a Web site:

MSC Direct (http://www.mscdirect.com/)

Here's a picture of the tapered bit:


394

[peter.j.meacham@lmco.com]

Group, do I presume correctly that using a tapered bit will produce a workpiece with tapered sides? thanks, Pete

[garbob]

Thanks. They look like nifty bits!

Gary

[rgbrown@itexas.net]

Pete asked:
"Group, do I presume correctly that using a tapered bit will produce a workpiece with tapered sides?"

Pete, probably so unless you have figured out a way to make the ShopBot 5 Axis.

You aren't holding something out on us are you?

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[bill.young]

Hey Ron,

You should have been at the Jamboree! Look about half way down the page at http://www.shopbottools.com/jamboree5.htm . Give it a minute to load...it's animated.

Bill

[billp]

Pete, Yes the cut does have a very slight taper, but in the depths we're speaking about it is barely ( if at all) noticeable. In some cases the taper might even be beneficial, such as adding "draft" when making molds..Bill P.

[ARTWORKBYKENWHITE@BIZEC.RR.COM]

bill, i spoke to you at the jamboree - we talked about scanning black and white photos - then saving as dxf files - and then ceating a toolpath
to carve by. i'd like for you to briefly {if possible} run that by me again.

[bruce_clark]

Bill,

I have not yet figured out the point of the taper endmill for regular routing. Other than draft angles (and making cool edges) what is the advantage of the tapered endmill?

BTW, I have had excellent results with solid carbide spiral O-flute bits made by Belin and they are less expensive. You can read more about them here:

http://www.multicam.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=TMS&Category_Co de=spiral-o

Bruce Clark

[billp]

Bruce, to my knowledge there IS no real advantage in a tapered bit. I bought it because it was the longest carbide 1/8" ball nose bit I could find! I needed the carbide because some of my work is in mahogany and I wanted to make sure the bit held up.As mentioned above, the taper has no real bearing on most cut files.If anyone knows of a longer carbide , ball nose bit, please let ALL of us know..

[billp]

Ken (KAW), I've forwarded the info to your e-mail address.BTW, they are not .dxf files ( to head off a gazillion other inquiries..). I use Artcam 5.1 to make up the images..

[garbob]

Bill Palumbo,

I just received the the two bits that you mentioned above. I cut 3/4" mdf at 1 inch per second. Very good cutting. I find that I can cut at this speed with a 1/4" spiral "O" Onsrud bit but the added dia. of the bit tears the small pieces off the 2 sided tape that I use to hold it down. I also received the "Big Book" from MSC, they aren't kidding, this is a big book. How did you ever decide on these bits from the other 10,000 in the book and why metal cutting bits?

Thanks, Gary

[billp]

Gary, I have been using "end mills'for the last few years. In many cases they are machined better, have more cutting flutes, and due to the fact they are manufactured in larger quantities, they're cheaper too! As mentioned earlier on the Forum, Chris Burns initially told me about the 1-1/2 inch tapered bit, and then I explored the "big book"and found the 2"version as well. I've been very happy with their longevity, and performance. If the taper isn't an issue they have MANY more bits in varying lengths, unlike the standard catalog found on most router bit lists. I believe that Shopbot will have a similar "bit set" for sale on the online "Shopbot Store" once they get that up and running..Keep digging in the "big book" and see what else you can find for us...!