Author Topic: How to guide OF 1010 properly along a curved edge?  (Read 3209 times)

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Offline shu

  • Posts: 12
How to guide OF 1010 properly along a curved edge?
« on: October 19, 2017, 06:40 AM »
Hi all,

I have to open a slot approx 30mm(edited) 6mm off the edge of a plywood for a LED strip. The edge is a random curve.

My router is 1010.

How can I guide the router properly?

Thanks in advance.

Shu
« Last Edit: October 22, 2017, 09:30 AM by shu »

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


Offline RKA

  • Posts: 916
Re: How to guide OF 1010 properly along a curved edge?
« Reply #1 on: October 19, 2017, 07:38 AM »
I think a better description or picture of the issue might help.  My first answer would have been to use a bearing guided slot cutting bit, buts that’s too easy, so I’m probably not understanding the issue you are having.
-Raj

Offline Roachmill

  • Posts: 36
Re: How to guide OF 1010 properly along a curved edge?
« Reply #2 on: October 19, 2017, 07:43 AM »
I've not done this but I'd start by thinking about making a template of the wavy edge with a guided straight bit.
Then take the template and position and secure it 30mm + diameter of bit I'd use away from wavy edge. I'd then use a short* top guided straight bit to follow the template. I'd also use a beefier router than the 1010 so take shallow passes (~3mm) if it's the only router available.

* "short" as in the height of the cutters is less than the thickness of the template (or vice versa) so the guiding bearing contacts the template before the cutter plunges into the plywood.

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #3 on: October 19, 2017, 08:50 AM »
1010 will be just fine for this operation. The slot shu is looking to cut will only be a few mm deep and 8-16mm wide.


Festool's copier scanning set  may work for you. #486534 & 486052.  Might not allow you to quite get 30mm inboard from three ge though. 

See this thread for insight :
http://festoolownersgroup.com/festool-how-to/how-to-use-copier-scanning-set/


This will certainly get you 30mm inboard of the edge.  If your curves are too tight it might not work either.

https://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/onpoint_router_plate.html


You could also make your own base with a fixed pin 30mm from the cutter.

Offline tjbnwi

  • Posts: 5271
  • Cedar Tucky Indiana
Re: How to guide OF 1010 properly along a curved edge?
« Reply #4 on: October 19, 2017, 08:51 AM »
CMT TMP-1200.

Festool used to market a copier set in NA. That works also.

Tom

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #5 on: October 19, 2017, 09:13 AM »
Tom ,  that might be useful too.  Quicker than making your own curved template for sure.

But it would require filling all the holes used to attach it to the piece.  That may not be desirable.

Offline Roachmill

  • Posts: 36
Re: How to guide OF 1010 properly along a curved edge?
« Reply #6 on: October 19, 2017, 09:19 AM »
I thought about the copier set. I have one, but I've never used it as yet with the reason being if you partially reorientate the router along the way (e.g. handle at 90 degrees to starting edge and you end up somewhere along the way now at 60 degrees) the cut line will not be equidistant to the corresponding distance at the start point. Like I said, I've never used it because of this but I could be wrong! It's also quite a spend for one wavy line ;)

Offline tjbnwi

  • Posts: 5271
  • Cedar Tucky Indiana
Re: How to guide OF 1010 properly along a curved edge?
« Reply #7 on: October 19, 2017, 09:19 AM »
Tom ,  that might be useful too.  Quicker than making your own curved template for sure.

But it would require filling all the holes used to attach it to the piece.  That may not be desirable.

Masking tape barrier and hot melt glue---no nail holes.

Tom

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #8 on: October 19, 2017, 11:33 AM »
Quote
Masking tape barrier and hot melt glue---no nail holes.

Tom

Now that's a clever trick.  Dots of glue or a continuous bead ?
Does the hot melt's heat affect finish ?


Offline Alex

  • Posts: 5478
Re: How to guide OF 1010 properly along a curved edge?
« Reply #9 on: October 19, 2017, 11:55 AM »
Make a screw-on base for the router out of very thin sheet material. Put two pins on the bottom that stick out. With the pins you can follow the curve and guide the router reliably along the edge.

Offline Michael Kellough

  • Posts: 2974
Re: How to guide OF 1010 properly along a curved edge?
« Reply #10 on: October 19, 2017, 12:04 PM »
Make a screw-on base for the router out of very thin sheet material. Put two pins on the bottom that stick out. With the pins you can follow the curve and guide the router reliably along the edge.

Until one of the pins goes off the end of the board.

I'd just clamp a piece of wood with the approximate curve to the router base but that only works if the curve is concave only or convex only. If it's a compound curve...go to Tom.

I don't now why we bother to answer a random question about a "random curve".
What is a random curve?

Offline blaszcsj

  • Posts: 293
Re: How to guide OF 1010 properly along a curved edge?
« Reply #11 on: October 19, 2017, 12:09 PM »
Quote
Masking tape barrier and hot melt glue---no nail holes.

Tom

Now that's a clever trick.  Dots of glue or a continuous bead ?
Does the hot melt's heat affect finish ?

Masking Tape down first then attach template with hot glue. The tape will prevent any harm to the wood finish.
OF1010 EQ Router | MFT/3 | DF500Q | Carvex 420 | ETS EC 150/3 | CT 36 Auto Clean | TS55 | LR32 | OF1400 EQ Router | ZOBO Metric Set | CXS Li 2.6 - 90 Limited Edition | Universal Cleaning Set | HKC55 | Centrotec CE-SORT |

Offline tjbnwi

  • Posts: 5271
  • Cedar Tucky Indiana
Re: How to guide OF 1010 properly along a curved edge?
« Reply #12 on: October 19, 2017, 02:04 PM »
Quote
Masking tape barrier and hot melt glue---no nail holes.

Tom

Now that's a clever trick.  Dots of glue or a continuous bead ?
Does the hot melt's heat affect finish ?

Continuous bead.

No affect at all on any I've ever used it one, directly or on tape.

Tom

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #13 on: October 19, 2017, 05:46 PM »
 [thumbs up]

Offline shu

  • Posts: 12
Re: How to guide OF 1010 properly along a curved edge?
« Reply #14 on: October 19, 2017, 07:10 PM »
While I'm digesting your suggestions and info, let me add more details on what I'm doing. So that you can check if I'm doing it properly [big grin]

I'm doing a climbing wall for kids. The base is 25mm plywood attached to battens fixed onto wall studs. The base is not full height. The top are curved in shape. Check the image for a templet for part of it made by 3mm MDF.
270415-0

Now I think it would be cool to have LED strip along the curved top, with light washing upwards.

But I don't want to see the LED directly. So I need a slot to hide it. Check the second image for the slot design.

The difficulty here is: on the one hand I should set the LED as far away from the edge as possible, to avoid the dotted effect and create a more smooth effect; on the other hand, I could not cut too far away as I need to allow enough number of screws as close to the edge as possible, so the plywood is structurally sound enough. I also don't want to create too big a slot, or anything to allow the kids to grab on the top edge of the board, when they climb close to it. As this is a weak part and I don't want them to get close to the LED either.

So please check the second image, which is the section view of the slot. It is quite tiny for the reasons above. I may need to do some test to see if it works. But before I start, I really would like to listen to your opinions.

270417-1

Regards.

Shu
« Last Edit: October 20, 2017, 08:20 AM by shu »

Offline Holmz

  • Posts: 3992
Re: How to guide OF 1010 properly along a curved edge?
« Reply #15 on: October 19, 2017, 07:22 PM »
Some Milky/translucent plexiglass cover over the LEDs.

Offline Alex

  • Posts: 5478
Re: How to guide OF 1010 properly along a curved edge?
« Reply #16 on: October 20, 2017, 03:43 AM »
Make a screw-on base for the router out of very thin sheet material. Put two pins on the bottom that stick out. With the pins you can follow the curve and guide the router reliably along the edge.

Until one of the pins goes off the end of the board.


Do the last half inch by hand?

Offline shu

  • Posts: 12
Re: How to guide OF 1010 properly along a curved edge?
« Reply #17 on: October 20, 2017, 09:56 AM »
Thanks everyone for your inputs.

RAK,
see reply #14 for more details.

Roachmill,
I think the template will be hard to make. The reason is that the template should be 30mm+dia of bit off the original curve. I can not trace the original curve as the offset curve will be a different one.

antss:
Thanks. I almost placed an order for the OnPoint plate, before I noticed the predrilled holes are not allowed for Festool 1010.
I also has a concern that the two-guide system will make the concave and convex setback slightly different from each other. With the convex setback more than 30mm, and concave one less than 30mm, I assume.
I may need a single guide one to maintain a continues setback. But that means I need manually make the moving line perpendicular to the curve all the time, which could be tricky.
I think I can somehow use the #486534 & 486052. I may need to make a base to attach them thou.

tjbnwi,
Thanks. It’s really good to know that. I'm now considering whether but it or not.

Roachmill,
Agreed. A not-perfect solution is to have a extension bar attaching to the router, with a handle at the end, as a control anchor. The longer the bar is, the easier to control. I guess the attached guide rail adapter will do.


Michael,
random curve is my freehand drawn curve made of lot of curves close to concave or convex.

Holmz,
will that cause the LED overheating?
« Last Edit: October 20, 2017, 10:20 AM by shu »

Offline RKA

  • Posts: 916
Re: How to guide OF 1010 properly along a curved edge?
« Reply #18 on: October 20, 2017, 10:41 AM »
@shu
You might be able to use something like a CMT flexible template.  But the tightest radius you'll achieve is probably around 2-3".  Use a template guide on the router and place some 1/2" ply behind the flexible template for support.  It won't give you a perfect offset off the edge, but it might be workable?  And the screw holes created when afixing the template will be on the back side, so that shouldn't be an issue. 

Once you have the channel for the LED routed, you should be able to raise the bit a little and hog out the remaining material out to the edge freehand. 

https://www.amazon.com/CMT-TMP-1200-Flexible-Template-Routing/dp/B008AXXH54
-Raj

Offline Michael Kellough

  • Posts: 2974
Re: How to guide OF 1010 properly along a curved edge?
« Reply #19 on: October 20, 2017, 11:44 AM »
Since the curve is compound, and the radius is tighter than the CMT flex template, and extreme fidelity to plan is not needed, you should go with Alex's suggestion to use two pins protruding from a sub-base you clamp to the router base.

Make the deep grove first then install a larger diameter bit and re-adjust the pin base and go again. If the wider shallower groove is not a 100% match/overlap of the first deep groove it shouldn't matter in this case.

To deal with my concern that you loose control when one of the pins is off the work you can just be very careful or clamp a guide to the work for the actual router base at the entrance and exit points.

Offline Gregor

  • Posts: 550
Re: How to guide OF 1010 properly along a curved edge?
« Reply #20 on: October 20, 2017, 07:41 PM »
I would solve it this way (as you have a router):
  • obtain:
    • sheet of cheap sheet material (for templating)
    • one slot bit (with same diameter bearing on the shaft) sized in diameter and depth (or deeper, then as a last step you'll need to make thicker copy of the final template) to the slot you want
    • one copy/flush trim bit (with bearing sized identical to the cutter, possibly you can use the first one for this too),
    • one displacement copy bit (smaller bearing than the cutter diameter, which will lead to a smaller copy than the original) sized so the intendet inner-side displacement of the slot is a multiple of that bits displacement (difference between the bearing and cutter radius)
  • make a 1:1 template of the original (the one you want the slot in at the end) with the copy/flush-trim bit
  • fit the displacement copy bit into your router, with the height adjusted so that the cutter covers slightly over* 50% of the material thickness
  • do a pass on the template, this will make a rabbet half the material thickness
  • flip the template over and repeat the process of the last step (guiding the bearing in the rabbet from the last step) until you reached the intended inward side displacement for the slot, then do a pass with the copy/flush trim bit to complete the creation of the inward side template
  • then make a template for the outward side of the intended slot (so you'll have templates on both sides of the intended slot which will fully prevent the router from wandering off as it'll be guided on both sides) by simply running the slot bit along the inward template into another template sheet - you could skip this step but it'll ensure that you will only destroy cheap template material instead of the original should you fail to guide snugly along the inward template
  • attach the templates(s) you ended up with to the original, use the slot bit to perfectly make the slot into the original - in case your slot bit would cut to deep you need to copy the templates onto thicker material first (or make them out of thick enough material in the first place)

EDIT: Hopefully clarified it a bit and added an outward template to the procedure, drop me a line in case you need a drawing to wrap your head around the concept (it is a recursive variation of templating for inlays).
In case you have a shaft mounted ball bearing bit that can be used for slotting where you can change the bearing and the cutter diameter is big enough so you can fit smaller one: you could get away with only that one bit (and two bearings, one same size to cutter and a smaller one), but having a higher displacement will speed up the process (by reducing the amount of passes you need to make on the template) and save quite some time (and reduce wear on the bit as of less passes).

EDIT: * exactly 50% is not needed, slightly over is enough. Modified the howto in that regard.
« Last Edit: October 22, 2017, 09:54 AM by Gregor »

Offline Dongar

  • Posts: 77
Re: How to guide OF 1010 properly along a curved edge?
« Reply #21 on: October 21, 2017, 08:15 AM »
I did not read the entire thread so I am not sure if this will help. Don
 

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #22 on: October 21, 2017, 08:24 AM »
That's a good how to video , but it's not applicable here at all.

shu's post on Oct. 19  will explain why.

Offline Gregor

  • Posts: 550
Re: How to guide OF 1010 properly along a curved edge?
« Reply #23 on: October 21, 2017, 01:32 PM »
That's a good how to video , but it's not applicable here at all.
Actually it applies, as it shows the offsetting action - just with a face displacement that adds material on the processed piece (relative to the template) instead of removing it as I suggested one post above his.

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #24 on: October 21, 2017, 04:45 PM »
Well,  it applies if you want say he's using a router and a template too.  I could post a how to on using a starting pin on a table and say " hey  this might help too " .  But it won't really.

The type of cut shu want to make can't be made on a router table very easily. Shu's piece is waaaaaaaay too big for starters. Being on the face instead of the edge is another problem for applying the video tips.

So , I will stand by my statement that the video really isn't very helpful for this project.

Offline shu

  • Posts: 12
Re: How to guide OF 1010 properly along a curved edge?
« Reply #25 on: October 22, 2017, 09:30 AM »
@RKA

Thank you. I may explore other method first for the simple reason that I may only do this kind of curve slot once. So if I have to buy something, I wish I can use it elsewhere.

@Dongar

Thanks. The video actually solves me another issue as I need to produce a negative curved thin MDF to cover the part of wall that's not covered by the plywood.

@Gregor,

Thanks for your step by step instruction. I do need a rough sketch to understand it if possible. Thanks in advance. I only have a 6mm straight bit without any bearing for this task. Can I install a bearing on the straight bit?

@antss,

Yes, my piece are way too heavy as well. The largest piece is 2400mm long and 1200mm tall, with 25mm in thickness. It would be even difficult to flip it over.

@Michael Kellough,

Is there any video or illustration I can use to understand @Alex's two pin method?
« Last Edit: October 22, 2017, 09:32 AM by shu »

Offline Gregor

  • Posts: 550
Re: How to guide OF 1010 properly along a curved edge?
« Reply #26 on: October 22, 2017, 09:53 AM »
Well,  it applies if you want say he's using a router and a template too.
He asked for a way to locate the slot ~30mm away from the curve he made, in a controlled manner, presumably with an OF 1010.
Quote
The type of cut shu want to make can't be made on a router table very easily.
But with the router handheld and the piece on the table (or some other support, even on the ground), so the size of the workpiece dosn't matter.
Quote
the video really isn't very helpful for this project
The video shows (among others) how to employ a router (and a template) to displace an edge (in- or outward) evenly over the whole length of it, regardless of that edge being straight or not.

@Gregor,
Thanks for your step by step instruction. I do need a rough sketch to understand it if possible.
Will prepare you one later today.
Quote
I only have a 6mm straight bit without any bearing for this task. Can I install a bearing on the straight bit?
I would suggest to get something like this (randomly picked from a google search, just to show how these look) to do all sorts of router based template work and something like this (again randomly picked for the looks) to make the final slot.

While you could also DIY a bearing onto your 6mm bit you'll need a bigger diameter cutter than the bearing to locate the edge toward the inside, this won't be possibly with the 6mm bit (and the wear on it when removing 30+mm material, even with several passes, would be immense).
Quote
Yes, my piece are way too heavy as well. The largest piece is 2400mm long and 1200mm tall, with 25mm in thickness. I would be even difficult to flip it over.
Won't be an issue, as you would only need to flip the template you create (which can be made from thinner, lighter material and thus be easier to handle).

Offline Gregor

  • Posts: 550
Re: How to guide OF 1010 properly along a curved edge?
« Reply #27 on: October 22, 2017, 02:20 PM »
See attached PDF (not to scale for anything) for visualisation of the principle to use templates for this.

Just seeing that I overlooked http://festoolownersgroup.com/festool-how-to/how-to-guide-of-1010-properly-along-a-curved-edge/msg526133/#msg526133 quite completely as I did the edit of the OP (sorry for that), principle would work nevertheless.
« Last Edit: October 22, 2017, 02:33 PM by Gregor »

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #28 on: October 22, 2017, 07:52 PM »
Quote
.

He asked for a way to locate the slot ~30mm away from the curve he made, in a controlled manner, presumably with an OF 1010.
Quote

    But with the router handheld and the piece on the table (or some other support, even on the ground), so the size of the workpiece dosn't matter.
Quote

The video shows (among others) how to employ a router (and a template) to displace an edge (in- or outward) evenly over the whole length of it, regardless of that edge being straight or not.


Shu started this thread by asking how to put a slot on a face of a board with a curved edge.   Not how to actually make a curved edge !   That's a whole different animal than what is in the video.  Shu doesn't want to displace and edge at all.  He merely wants to follow one he already has.

Now, a large template is one way to do what shu wants -  and that has been suggested already.  He could also purchase the CMT jig suggested that would be faster and reusable and easier to handle.   But again, none of which will be done on a router table with any amount of safety.

Shu's project is going to need to be done with a handheld router.

Offline Gregor

  • Posts: 550
Re: How to guide OF 1010 properly along a curved edge?
« Reply #29 on: October 23, 2017, 01:18 AM »
@shu corrected PDF attached.

@antss:
As you're the only one who brings up 'router table' I'm at a loss about what your point might be. Stuff might have been lost in translation (as I'm no native speaker), but I get your hint that I'm just an offtopic idiot that tried to help but failed miserably.
So I'll just stop. Sorry for distracting.
« Last Edit: October 23, 2017, 01:51 AM by Gregor »

Offline Cheese

  • Posts: 3613
Re: How to guide OF 1010 properly along a curved edge?
« Reply #30 on: October 23, 2017, 09:44 AM »
Some Milky/translucent plexiglass cover over the LEDs.

Exactly...this is what I'm doing for some built-in cabinets. The translucent cover does a great job in reducing the individual LED "spotlight" effect. Most of the strip LED suppliers offer these covers in different widths and lengths.

The 2nd photo gives you an idea on how even the LED beam spread is with the cover in place.

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


Offline shu

  • Posts: 12
Re: How to guide OF 1010 properly along a curved edge?
« Reply #31 on: October 23, 2017, 10:24 AM »
@Gregor,
Thanks so very much for the impressive illustrations. The solution is very straightforward and easy to follow. Are the template bits set in your link the only thing I need to buy?

@antss,
Thanks a lot for helping others understanding my questions!

@Cheese,
Thanks. I do prepare to try a cover if the test result is not ideal.


Offline shu

  • Posts: 12
Re: How to guide OF 1010 properly along a curved edge?
« Reply #32 on: October 23, 2017, 10:48 AM »
It seems the bit set is 1/2" which can not be used on 1010.

Am I looking at something like this?

Offline Michael Kellough

  • Posts: 2974
Re: How to guide OF 1010 properly along a curved edge?
« Reply #33 on: October 23, 2017, 11:05 AM »
It seems the bit set is 1/2" which can not be used on 1010.

Am I looking at something like this?

Try this rabbeting bit set from Lee Valley. It has an 8mm shank.

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #34 on: October 23, 2017, 12:19 PM »
Gregor , your solution is very elegant , drawings through and your English is much better than my Deutch.

It has a too many steps and requires too much material for my tastes though.

The sub base and pin method Alex and I suggest requires less steps, material , and router bits to accomplish.  Even the  CMT flex template and a mortise bit would be less complicated.

What matters though, is what shu finds to be most effective.  He seems to have reservations about guiding the router along the edge with an index pin(s).  So if your way with all the templates and router bits gets him to the finished project , it's a good one.

Offline Gregor

  • Posts: 550
Re: How to guide OF 1010 properly along a curved edge?
« Reply #35 on: October 23, 2017, 12:42 PM »
It seems the bit set is 1/2" which can not be used on 1010.

Am I looking at something like this?

Try this rabbeting bit set from Lee Valley. It has an 8mm shank.
Yes, something like that would do in case it enables the dimensions you need.
As I wrote:  the ones I linked were just to show how these kind of bits look - as I have no clue how these are named across the ocean and which places sell ones that last while not being overpriced... I just used a google image search.

A full set with a thin bit, a thick bit and a pile of different sized bearings might be interesting in case you plan to do more template work in the future, as such one allows to create and manipulate a wide range of templates (creating positive/negative ones for inserts, perfectly joining two kinds of wood along a non-straight seam, other fun stuff).
« Last Edit: October 23, 2017, 12:51 PM by Gregor »

Offline Alex

  • Posts: 5478
Re: How to guide OF 1010 properly along a curved edge?
« Reply #36 on: October 23, 2017, 01:19 PM »
@Michael Kellough,

Is there any video or illustration I can use to understand @Alex's two pin method?

Why ask Michael and not Alex? Hm.  [scratch chin]





Shopped this together with a pic I found on the net. The two pins on the base will let you follow any curve.

The steeper the curve the closer the pins need to be together. With a smoother curve you can space them a bit wider for better stability.

Just take it slowly when you work and make sure both pins stay in contact with the edge. Since the slot is completely hidden you don't need to worry too much about precision.
 

Offline antss

  • Posts: 1378
Re: How to guide OF 1010 properly along a curved edge?
« Reply #37 on: October 23, 2017, 01:25 PM »
Quote
Since the slot is completely hidden you don't need to worry too much about precision.

When the question first came up I was thinking this was for a shelf where you could see the slot when installed.   Now knowing that isn't the case , I'd probably just mark a line 30mm off the edge and free hand the groove.

Won't be as neat as one of these other methods, but it'll be done in an hour and ready to install lights.

Offline shu

  • Posts: 12
Re: How to guide OF 1010 properly along a curved edge?
« Reply #38 on: October 23, 2017, 06:45 PM »
@Alex,

Thanks a lot for the photo and explanation. I now fully understand what the two pin means.

@antss

I'd eager to learn and explore all possible solutions.
If I have conservation, my only concern is:
If the distance between the bit and the line connecting the two pins is fixed(we call it A), the setback of the cut slot to the edge depends on the shape of the curve. If it's convex, the setback will be shorter; if concave, longer. And the more curvature, the more difference.

As the change of the curve is consistent, I have no way to change the distance A accordingly. Therefore I will end up have a slot that never parallels to the original curved edge.

PS. I told a lie that I actually need to have the slot 6mm off the edge, in lieu of 30mm. So precision will be required and freehand is not an option here.

Can I summerise:
Two pin method give bests control, but is more suitable for a curve with unchanged curvature, when precision required.

@Michael Kellough @Gregor, Thanks, I will go for the Lee Valley one.
« Last Edit: October 24, 2017, 07:22 AM by shu »