router spiral bit grabs, ruins cut - Page 2 - Woodworking Talk - Woodworkers Forum
 22Likes
Reply
 
Thread Tools Display Modes
post #21 of 60 Old 08-14-2020, 10:44 AM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 27,547
View woodnthings's Photo Album My Photos
Using a jig or a fixture?

here's the difference explained:
https://www.google.com/search?client...+and+a+fixture
Quote:
A jig is often confused with a fixture; a fixture holds the work in a fixed location. A device that does both functions (holding the work and guiding a tool) is called a jig. An example of a jig is when a key is duplicated; the original is used as a jig so the new key can have the same path as the old one.


A fixture holds the part for it's cutting or routing operation.
A jig may hold the machine or the workpiece and does both operations depending.
Splitting hairs a bit I suppose but, what I have proposed is a fixture to secure the part in. I like routing from above the workpiece rather than "upside down" as on a router table for small parts so I can see what actually happening. The large surround I proposed carries the weight of the router and also provides a smooth level support.
The router base is framed in by stops to limit it's movement in the X and Y directions.

I suppose you could make an upside down fixture to hold the part on the router table, BUT elevating the bit into the work for each pass requires a lift or a router with an above the table height adjustment. And limiting the travel in X and Y may prove more difficult .... probably requiring stop on the fence and the table.

For long, straight runs, a router table is fine or for the ends of short boards for rail and stiles then a table is best. It still requires a secure means to hold the material, preferably clamped.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is offline  
Sponsored Links
Advertisement
 
post #22 of 60 Old 08-14-2020, 11:23 AM
Senior Member
 
TomCT2's Avatar
 
Join Date: May 2014
Location: Central PA
Posts: 1,455
View TomCT2's Photo Album My Photos
if I ruled the world . . . I'd try this:
router spiral bit grabs, ruins cut-img20_952.jpg

the notch is the size of the work pc but slightly short, so that

(a) put work pc in notch
(b) squeeze tight end-to-end with clamp block
(c) tighten nuts on all thread to hold everything securely.
obviously you'll need decent width/length cut accuracy - the clamping will not accommodate +/- 1/4"

the clamp block needs to be able to slide - so elongated hole(s) required either thru the block or thru the notched body "legs"

given all the center material hogged out, I wonder if the up-spiral is necessary.
the up cut is most useful for grooves/deep dados/mortises where there's no place for the chips to go....
if you're using a vacuum collection, chips thrown into the hogged out area should 'disappear' in the air stream.....


I'd also be tempted to use some spacers in the router table jig to first knock off the big chunks between bore holes, then a second pass with less variable force needed.... taking a light skim pass is always easier than heavy cuts....
TomCT2 is offline  
post #23 of 60 Old 08-14-2020, 09:04 PM
Member
 
hoowasat's Avatar
 
Join Date: Dec 2019
Location: NN, VA
Posts: 90
View hoowasat's Photo Album My Photos
Quote:
Originally Posted by difalkner View Post
How deep of a cut are you taking, Bruce? Is it possible to do the cut on a larger piece and then cut it down to the size you need just to be safer and have more to hold for the cut?

David
I agree with David in that it seems you may need to remove material using multiple passes. You're getting tear-out where the bit is cutting against the grain. Perhaps 2 fixtures would help ... the first for incremental passes until you are almost at full depth ... and the second to finish cut the outer surfaces and bottom.
difalkner likes this.

Ken
Everything works out in the end. If it's not working, you're not at the end.
hoowasat is offline  
Sponsored Links
Advertisement
 
post #24 of 60 Old 08-14-2020, 09:52 PM
Senior Member
 
Join Date: Jul 2016
Posts: 834
View Terry Q's Photo Album My Photos
My Leigh FMT makes similar shaped mortises by holding the wood securely and using a plunge router to hog out the wood. Maybe you need to rethink using a router table.

It is quick, less then a minute to route normal sized mortises. Safe, plunging keeps your hands far away from the workpiece. Clean, never had chipping like you show.

Like others have suggested, leave the work pieces as long as possible, mark the center of your holes and slide the workpiece along, using a plunge router and template on top to hog out the wood.
Tool Agnostic likes this.
Terry Q is offline  
post #25 of 60 Old 08-15-2020, 12:46 AM Thread Starter
Member
 
Join Date: Feb 2019
Posts: 70
View brucet999's Photo Album My Photos
I appreciate the concern for safety, but doing holes on a large piece of stock, then cutting afterward is impossible. The whole point of the dovetail sliding-lid box is to cut the lid from the same piece of VG lumber such that when the dovetail cut is made and the lid is cut with matching 14 edges, the closed lid becomes almost invisible. I must work with 2" x 3" x 1 3/4" blanks.

Moosie's suggestion to make a holder fixture with which to move the work piece, with large handles farther apart to give me better grip and keep fingers away from 16,000 rpm sharp things appeals to me. Moving the work instead of the router means that I can keep the router mounted to the table where it must be in order to do the dovetail cuts and the rounding-over of the edges of the finished boxes.

So would a CNC machine appeal to me, if I had the thousands of dollars to buy one that could handle a 1/2" spiral bit and if I had sufficient space in my shop for it.

BruceT
brucet999 is offline  
post #26 of 60 Old 08-15-2020, 01:04 AM
Junior Member
 
Join Date: Aug 2020
Posts: 14
View moosie's Photo Album My Photos
Quote:
Originally Posted by brucet999 View Post
Moose, I think I can visualize part of your "upside down sled" idea, but 5 times the length and width would make it a 15" x 10" sled.

The hardwood cleats idea makes no picture in my mind. How would I hold the box on the under side of the sled?

With such a big sled, how would I see to place my box inside the jig? As it is, I have to pivot the piece a little while putting it in the jig so as to gently plunge the bit into the bottom of the box. taking off 1/32" of material to smooth out the forstner bit grooves.
I was off with the 5x sled size. Mentally I was trying to get your hands away from that bit. Maybe sled isn't the right word. More like 'handle'. See my attached diagrams (very quickly done, so use your imagination).

Green is router table, and green cyl is the bit. Yellow workpc. I don't show your fence that limits travel. You just need to be aware of heights so my cleats don't hit your fence. Cleats are in blue. Attached permanently to the red sled/handle. The red cyls are just grab points (handles for the handle). You could set your workpc over the non-spinning bit, and fit the cleat/sled down over the top. Lay it on top. Press down. You control the piece, even though it's not attached to the sled. Now push the workpc around in whichever lateral motion you want (climb cut even).

This whole idea, and any other, IMO, must be only for skim cleanup. Like the last 1/16. Take very small bites. Visibility might be an issue, but in a way it's more psychological, no? You have the stops/fences. You have the piece firmly pressed to the table. You can't see the inside of the box anyway... But, you could use 1/4" plexi for the sled.


Re the skim cleanup, here's an example that may help. I make solid body guitars. I cut the body shape out of an 8/4 blank with a bandsaw, zipping around the curves using a 1/4" blade and staying mebbe 3/16" from my line. Then it gets a ride on the bench and spindle sanders, removing wood all the way to just kissing the pencil line. All that's left is probably 1/32". Because there's so little wood for the router, I can run the Whiteside 2" CL spiral at full height, running it around that body, in both directions. There's no hint of danger or fear. But if I were to leave a fat 1/16" on there instead? I might lose something, and not just the workpiece. I see your situation as similar, just inside-out, and much smaller, closer.

Hope this helps a bit.
Attached Thumbnails
Click image for larger version

Name:	Screen Shot 2020-08-15 at 12.35.53 AM.jpg
Views:	14
Size:	169.6 KB
ID:	393869  

Click image for larger version

Name:	Screen Shot 2020-08-15 at 12.37.19 AM.jpg
Views:	14
Size:	185.1 KB
ID:	393871  

moosie is offline  
The Following User Says Thank You to moosie For This Useful Post:
brucet999 (08-16-2020)
post #27 of 60 Old 08-15-2020, 11:47 AM
Senior Member
 
Join Date: Aug 2017
Posts: 2,998
View Tool Agnostic's Photo Album My Photos
I am with those who suggest making a workbench holder for the workpiece with a template above the workpiece. Use a plunge router with a guide bushing from above.

It is easy to set the plunge depth to make several passes, starting with a shallow pass.
Tool Agnostic is offline  
post #28 of 60 Old 08-16-2020, 02:51 AM Thread Starter
Member
 
Join Date: Feb 2019
Posts: 70
View brucet999's Photo Album My Photos
Thanks @moosie. I thought about your suggestion and at last pictured the cleats much as you have drawn them. I plan to make a fixture similar, but split into two pieces along a line perpendicular to a line drawn from one corner of my rectangular work piece to the opposite one. Today I bought a cam clamp at Rockler and will use that with a bolt through two cleats fastened on the top of the fixture halves so that it will quickly clamp the cleats firmly to the work piece and allow a quick release as well. The blanks are 1 9/16" high, so 5/8" cleats will leave plenty of clearance from my 3/4" thick limiting jig mounted to the table.

I plan to use @Dave McCann's suggestion to first drill out the corners of the blank, using a 1/2" forstner bit just 1/16" in from the final dimensions of the corners, then switch to my 1 1/4" forstner to drill right, left, and center. That should leave just a little bit of clean-up to do with the spiral bit.

My Bosch router motor can be raised in 1/2" increments, so to be extra safe, I'll run a first pass at 11/16" depth, then second at full 1 3/16" depth. For 70% of the first-batch pieces, hand held, I got good clean cuts even with only the two 1 1/4" forstner bores, so I am confident that the problem will be solved.

BruceT
brucet999 is offline  
post #29 of 60 Old 08-16-2020, 04:23 AM
Senior Member
 
Join Date: Sep 2014
Location: East Anglia
Posts: 182
View fareastern's Photo Album My Photos
Quote:
Originally Posted by brucet999 View Post
I appreciate the concern for safety, but doing holes on a large piece of stock, then cutting afterward is impossible. The whole point of the dovetail sliding-lid box is to cut the lid from the same piece of VG lumber such that when the dovetail cut is made and the lid is cut with matching 14 edges, the closed lid becomes almost invisible. I must work with 2" x 3" x 1 3/4" blanks.

Moosie's suggestion to make a holder fixture with which to move the work piece, with large handles farther apart to give me better grip and keep fingers away from 16,000 rpm sharp things appeals to me. Moving the work instead of the router means that I can keep the router mounted to the table where it must be in order to do the dovetail cuts and the rounding-over of the edges of the finished boxes.

So would a CNC machine appeal to me, if I had the thousands of dollars to buy one that could handle a 1/2" spiral bit and if I had sufficient space in my shop for it.

I'm having difficulty with understanding the problem. For this kind of job I would rip the strip that makes the sliding lids after pencilling a few locating lines on one edge to assist with correct alignment.Having a longer blank to work with also reduces the chances of pieces splintering out in the corners as the greater length of material between the pockets increases the force required to generate breakout.I see at least one other poster agrees with the notion of using a template from above but given the requirement to leave the router mounted,the alternative jig will work.


Just for information,my home made CNC router has a work area of about 14"X10" and cost me about the same as a decent half inch router.Plus a bit of thinking.
fareastern is offline  
post #30 of 60 Old 08-16-2020, 11:49 AM
Senior Member
 
TomCT2's Avatar
 
Join Date: May 2014
Location: Central PA
Posts: 1,455
View TomCT2's Photo Album My Photos
"...then switch to my 1 1/4" forstner to drill right, left, and center."


fyi....

this may be very problematic without iron fisted clamping.
it's a "interrupted cut" - the bit will likely "trip" on the pointy bits left from the left/right drill holes.
TomCT2 is offline  
post #31 of 60 Old 08-17-2020, 02:19 AM Thread Starter
Member
 
Join Date: Feb 2019
Posts: 70
View brucet999's Photo Album My Photos
Thanks for the pointer. Maybe I should drill center first, then left and right held against the stops.

BruceT
brucet999 is offline  
post #32 of 60 Old 08-17-2020, 03:34 PM
Senior Member
 
TomCT2's Avatar
 
Join Date: May 2014
Location: Central PA
Posts: 1,455
View TomCT2's Photo Album My Photos
I'd be tempted to do six half inch drills, then the left/right 1.25 inch. that will leave a consistent flat platform for the big drill.
Attached Thumbnails
Click image for larger version

Name:	block_1.jpg
Views:	12
Size:	25.0 KB
ID:	394003  

Dave McCann and moosie like this.
TomCT2 is offline  
post #33 of 60 Old 08-17-2020, 03:45 PM
Senior Member
 
Join Date: Jun 2020
Posts: 116
View Dave McCann's Photo Album My Photos
Quote:
Originally Posted by TomCT2 View Post
I'd be tempted to do six half inch drills, then the left/right 1.25 inch. that will leave a consistent flat platform for the big drill.
Tom,
Nice layout, Having a guide plate for the 1/2 inch holes, would allow for consistent and quick positioning of the drill.

Take care,
Dave McCann
Dave McCann is offline  
post #34 of 60 Old 08-18-2020, 12:31 AM Thread Starter
Member
 
Join Date: Feb 2019
Posts: 70
View brucet999's Photo Album My Photos
Quote:
Originally Posted by TomCT2 View Post
I'd be tempted to do six half inch drills, then the left/right 1.25 inch. that will leave a consistent flat platform for the big drill.
What does "consistent flat platform" mean?

From the first picture you can see that I ground off the brad point of an old 1 1/4" forstner so I could drill deeper, leaving less for the spiral bit to clean up. I don't want to ruin my 1/2" forstner by grinding its point off, so I can only drill about 1/8" shallower than the 1 1/4" bit. Still, those little benches should be no problem for the router bit.

BruceT
brucet999 is offline  
post #35 of 60 Old 08-18-2020, 09:37 AM
Senior Member
 
TomCT2's Avatar
 
Join Date: May 2014
Location: Central PA
Posts: 1,455
View TomCT2's Photo Album My Photos
forstner have a big flat blade on the bottom - a flat, symmetrical, consistent "surface" to drill thru gets the best results. spade bits have similar issues but even worse.



if you've every tried to make a half-round notch at the edge of a board.... that's the same issue. the bit will not want to drill straight, it will wander away from straight toward the 'empty' side. for notches, I clamp up some scrap and drill a "complete" hole....


which is also the issue drilling thru the two 'points' in the center - the bit 'catches' on them - either the wood gets torn up or it breaks loose from the clamping, and that's another mess....
woodnthings likes this.
TomCT2 is offline  
The Following User Says Thank You to TomCT2 For This Useful Post:
brucet999 (08-19-2020)
post #36 of 60 Old 08-18-2020, 10:00 AM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 27,547
View woodnthings's Photo Album My Photos
This would make all this much easier ....

Originally Posted by woodnthings
Another approach is to bandsaw out the center opening by making an entrance cut for the blade and then gluing it back together. This would require a separate bottom also glued on afterwards.


Quote:
Originally Posted by TimPa View Post
great idea!!

The glue line(s) would be virtually invisible and the center "waste material" would be gone in less than a minute.... WAG?



Start with a long strip as thick and as wide as the finished block. Slice 1/2" or 3/8" off the bottom but keep the orientation for the glue up later. Crosscut into smaller lengths as desired. Using a holding fixture, rout out the centers using the fixture for uniformity. There will be very little to remove after the bandsaw cut, saving time and wear and tear on both the router and the cutter. Glue the bottoms on, close up the saw kerf, sand it all flush and "away you go"

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is offline  
post #37 of 60 Old 08-27-2020, 11:56 PM Thread Starter
Member
 
Join Date: Feb 2019
Posts: 70
View brucet999's Photo Album My Photos
Thank you, Moosie, for the idea for a clamping fixture with handles to hold my little box blanks with hands safely away from the bit. Here is what I made, including quick release cam clamp. The little bit with the string is a spacer to keep the two halves from canting inward when I put pressure on the clamp.





I have no idea why the two pics show up at different sizes. Oh well. :)
moosie likes this.

BruceT

Last edited by brucet999; 08-27-2020 at 11:58 PM.
brucet999 is offline  
post #38 of 60 Old 08-28-2020, 12:05 AM Thread Starter
Member
 
Join Date: Feb 2019
Posts: 70
View brucet999's Photo Album My Photos
@ TomCT2, I appreciate your warning about trying to use the 1 1/4" bits at the ends after drilling the center. I hadn't done the math to realize that each one would be working on 1/2" of wood surface.

I modified my jig for quick change from a set-up for 6 borings with 1/2" forstner bits, to the two borings with 1 1/4" forstner, using just a couple of inserts. No need to re-align and re-clamp the jig to my drill press table.

BruceT
brucet999 is offline  
post #39 of 60 Old 08-28-2020, 12:25 AM
Junior Member
 
Join Date: Aug 2020
Posts: 14
View moosie's Photo Album My Photos
Quote:
Originally Posted by brucet999 View Post
Thank you, Moosie, for the idea for a clamping fixture with handles to hold my little box blanks with hands safely away from the bit. Here is what I made, including quick release cam clamp. The little bit with the string is a spacer to keep the two halves from canting inward when I put pressure on the clamp.





I have no idea why the two pics show up at different sizes. Oh well. :)
You make prettier jigs than I do...

Does it help with the original problem?
moosie is offline  
post #40 of 60 Old 08-28-2020, 07:45 AM
Moderator
 
John Smith_inFL's Avatar
 
Join Date: Jul 2018
Location: Central Florida
Posts: 2,947
View John Smith_inFL's Photo Album My Photos
Bruce - if this is going to be an on-going project,
can you have another drill press and router in your budget ?
if you are getting into a crunch with changing bits and cutters,
more tools in the assembly line can lessen the "handling hassle" greatly.
especially if it is just you on the assembly line.
looking forward to following your journey in this project.

John

.

there is no educational alternative to having a front row seat in the School of Hard Knocks.
John Smith_inFL is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome