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Drilling the canopy

Bavafa

Well Known Member
In drilling the canopy, I used a drill bit for plastic (118 tip) from McMaster with not so good results. When looking at the holes with a magnifying glass from inside, on some of the holes there is a chip on the exit point. (I have deburred the holes which has taken roughly 70-80% of the chip out but not all. From what I can think, here are my options:

1- Deburr more to take all the chip out but it will make a semi (small) countersink on the inside
2- I can use a Plasdrill bit which have had great results with but they are not available in the number sizes and 5/32? would be my next size which makes my current hole of #27 to a 5/32? hole.
3- Don?t be picky and leave it as is
4- Your suggestion
5- Your recommendation


Thanks in advance
 
Mehrdad
It's been a couple years since I did my canopy but my initial holes were all number 40 and then any holes after that you want to have a backer made of wood or UHM , if you need to use one of your regular bits you can dul them by drilling into your concrete floor for 10-15 seconds and the only thing you can use it for now is plexi
Give your glass all the room you can to expand & contract ,,, 2 Of the 4 RVs in my county have cracked canopies rite now , fingers crossed every time I close mine these cold mornings !
 
Find a scrap piece of canopy. Get a brand new uni bit and practice with it. I have found it works the best. Nice clean hole and it de burrs.



Bob Grigsby. Los Altos. Ca
3B. Close
J3 flying Low and slow. Usually at pattern altitude. Clint at Vetterman wanted to know "why so high?"
 
On my plexiglas and lexan canopies, I generally use a small UniBit for the majority of the holes. Sometimes it results in a hole that is ever so slightly larger than the plans-specified hole -- but that is OK with me since the extra hole clearance provides slightly more room for the expansion/contraction of the plastic material. Another benefit of the UniBit is that you can very carefully use the next larger UniBit drill step to gently chamfer the edges of the hole. As noted above, practice on scrap material to build your confidence and perfect your technique. Also, be sure that the plastic material is warm!
 
Make sure the Temperature is warm enough

Plexi does not like to be drilled if it's too cool. Check me on this, but I think 65 degrees is considered a minimum. 85 is better.
 
make your own bits

if you take the drill size you want ( old and dull is ok) then use a Dremel with an abrasive disc.....put the bit in a vise, get out your reading glasses, and then take the 'rake' out of the bit.
grind the face of the cutting edge completely vertical, in line with the long axis of the bit. Some guys also point the bit like the fancy ones, but it's not entirely necessary.
You now have a milling tool.....much like the unibit.
It will SCRAPE it's way thru the acrylic, and won't 'grab' as you exit.

As other's have said, be sure you have a good, solid backup, and just go right into it so the hole in the acrylic is a nice cylinder.

smart to test, test, test before doing the real thing.
You'll know by the sound..... the rpm.... and pressure ....and speed of cut that makes nice curlies, and those that don't!
 
Lots of good advise, none applies to my situation as I have already drilled it and honestly the chip is so small that can not be seen without a naked eye.

I have done the backing it with a piece of wood method when is possible, the canopy is backed by its frame and not possible to back it with a piece of wood. Also a uni-bit will not work with thick material unless you don't care about the size. If one is OK with going to a slightly larger size hole, I highly recommend a Plasdrill, you can get it at skygeek or Tap plastic. It works very nicely.

http://www.skygeek.com/craftics-110...MI5JbryY762QIVUoZ-Ch2a3Q5dEAYYBSABEgIJ9fD_BwE
 
Plexi does not like to be drilled if it's too cool. Check me on this, but I think 65 degrees is considered a minimum. 85 is better.

They don't like hot either, so, when drilling many holes, the bit gets hot. Just dipping the bit in a cup of water before drilling provides enough lubrication and cooling to make a much cleaner hole. I discovered this when drilling dozens in plexiglass for a different project. It made a significant difference.

BTW - I use the Avery bits that look more like these.

c7IRCVS0wpJAw54MCwmTDl_7Rz3gr2tTvE9jW-Wb4QwnKDiHjSFk2RT22S7h1O8NL2W7ZduVe8tH8tro1LWNwUALk395Yefp2vkn6dBMLzqeaq13YiNNS5LKSzIWp4BuRf_x8IfTDwsz5gGastjrNHxzKElajGGitxzk5l4itbibT1ONE5HgyMFZL9sLA6VXE5hFeNX3Vg9dbAjaMLIWuL_sYWovOvx4osjHf8_c1A2LAhxbTiprOJYqLY-LP1piRZ5GfXBOfA4Wg_kpIo0Bl1y9qpb0kKsJqHpLUD-rA5UV0kBV7eZ580NeF9AsuZF-CjtjToZV09Q9FrWLi0Id2VYeXlb6Xvk-qHpWTlaNr3eLCAQYdy7mT_zP-QFb9ItRWxzFi_RJhZBUSZXJl0sOmR_ugE6rnqyphi9cPcVaPtmYTdPML2NeIOhlW5roRFaWG_lE-eOY8U3IKSl0gpmZ7Sg3_GyOgAxdpLMK66GICU0r4PXfBgpLU5UTli9YRVw7QUo0La5bxD2MvVj32u-dKVn7J5TzCZ1rV4KBC6SzRsFzBzZe7scUMliaR4pVX-RGHYodyHN8zDf1pQwTq1FA85sphDwBD2bPrVsyWZHZ_J8DtYCFAtlhoNjmuqXwLZAwD7v1HndSrEMLFSyWAKYS6RUeDidf2aJg=w400
 
I plan to buy permagrit 100 degree counter sinkers to counter sink. They might be able to clean up the hole edge if used carefully.

Go to this site for drill bits of all numbered sizes for plastic. I just bought some.
https://www.abbeon.com

Just a thought, since I have not yet done this step.

I emailed vans about scrap plexiglass. I got an call from the canopy manufacturer and 3 days later I have scrap plexiglass. I just had to pay shipping.

good luck.
 
Mehrdad,
I think you need to get all of the chipped areas out of the holes you've drilled. A chip is a stress riser, and under the right conditions of temperature and load near the hole, it will crack. If additional countersinking won't get rid of the chip, you'll need to drill a larger hole with a clean cut. Countersink this hole, make it smooth, and if it's larger than the head of the installed rivet - not to worry.... use a countersunk washer to capture the rivet head and spread the load out to the hole. I made all my drilled holes in my canopy 2X the diameter of the rivet shank to allow movement. Not only countersinking, but polishing all cut and countersunk edges in the plexiglass will reduce stress riser areas, and allow easier movement with temperature changes. Make sure you use soft pull rivets for canopy installation if you are using rivets for attachment - not the best plexiglas attachment method by the way. You can't regulate the pull on the rivet, and even 'soft pull' rivets pull too tightly.
 
EAA videos!

There's an EAA video on this subject. He even shows you how to modify a standard bit. This is the method I use, and I drill hundreds of 9/32 holes in plexi every week.
 
Enlarging holes?

I am ready to drill my back window and see several different techniques. I checked what Vans published and found the following in 5.19:

- To enlarge holes the use of a step-drill (Unibit) or reamer is recommended.

- CAUTION: Using a regular twist or plexi drill to enlarge a pre-drilled hole is not recommended and will practically guarantee a cracked canopy as a result.

So if I follow Vans guidance, I should not use a plexi drill to enlarge holes. I have looked for a step drill that goes from 40 to 36 to 27, but apparently that does not exist. The only other option above from Vans recommendation is to use a reamer. I have a 36 and 27 straight flute reamer. I have seen no one on the forum mention using a reamer to enlarge the holes.

Two questions:
1. Has anyone used a reamer to enlarge the 14 plexiglass holes from 40 to 36 to 27 as the plans dictate?

2. What am I missing on the unibit guidance and how do I use a unibit on such small holes?

-------------------------------
Rob
RV-14 Finish Kit in the Works
 
I am ready to drill my back window and see several different techniques. I checked what Vans published and found the following in 5.19:

- To enlarge holes the use of a step-drill (Unibit) or reamer is recommended.

- CAUTION: Using a regular twist or plexi drill to enlarge a pre-drilled hole is not recommended and will practically guarantee a cracked canopy as a result.

So if I follow Vans guidance, I should not use a plexi drill to enlarge holes. I have looked for a step drill that goes from 40 to 36 to 27, but apparently that does not exist. The only other option above from Vans recommendation is to use a reamer. I have a 36 and 27 straight flute reamer. I have seen no one on the forum mention using a reamer to enlarge the holes.

Two questions:
1. Has anyone used a reamer to enlarge the 14 plexiglass holes from 40 to 36 to 27 as the plans dictate?

2. What am I missing on the unibit guidance and how do I use a unibit on such small holes?

-------------------------------
Rob
RV-14 Finish Kit in the Works

Rob,
The issue with using a unibit, unless you can find one that has the adequate depth for each step, is that it works well for thinner material but for thicker material as you go deeper, you will get to the next size.

Take a look at a Plasdrill bit and Tap plastic has a video of it that shows how clean they drill into plastic. I have them and I can attest to the job they do. The only thing is that they don?t come in a letter type drill bit and the closes size to the #27 is a 5/32? which is slightly larger than #27.

https://www.youtube.com/watch?v=9mxZMXCjDuA

On parts that you can support the back of it, like the back window, have a person to protect the back side of the window that is being drilled with a piece of wood. This method will greatly reduce the chance of chipping.

I have drilled many pieces (both practice and actual) with a #40 and then finished it with the Plasdrill. I even used the 5/32? bit on the hole that I had got the chip and it took out the chip cleanly.

McMaster has #27 drill bit for plastic but it was a disappointment as they did cause chip. Finally warmer temp is your best friend.

Good luck
 
The hole made by the 36 bit is to tap the plexiglass and the roll bar at the same time. Could you skip this and just match drill a #40 hole, then drill out and tap the roll bar with a #36. Then just go from a #40 to a #27 in the canopy? I know that the recommendation is match drill #36 canopy and roll bar so you can tap the canopy and roll bar together to get a straighter tap.

Wouldn't a reemer suffer from the same issue as a regular drill bit. In that, the point when the hole is enlarging at the back side there will be a point with a very thin piece of plexiglass that would chip off. That is why a drill bit with the outer edge sanded off helps alleviate this issue.

Is there a potential issue with cracking when tapping the hole in the canopy?

I also plan to use the following to counter sink. I figure that grinding the counter sink would be better than cutting.

https://www.permagrit.com/kt2/

Also cabinet scrapers seem to be a great tool to finish off edges.

I plan to start canopy soon, so I am very interested in this topic.
 
The hole made by the 36 bit is to tap the plexiglass and the roll bar at the same time. Could you skip this and just match drill a #40 hole, then drill out and tap the roll bar with a #36. Then just go from a #40 to a #27 in the canopy? I know that the recommendation is match drill #36 canopy and roll bar so you can tap the canopy and roll bar together to get a straighter tap.

Wouldn't a reemer suffer from the same issue as a regular drill bit. In that, the point when the hole is enlarging at the back side there will be a point with a very thin piece of plexiglass that would chip off. That is why a drill bit with the outer edge sanded off helps alleviate this issue.

Is there a potential issue with cracking when tapping the hole in the canopy?

I also plan to use the following to counter sink. I figure that grinding the counter sink would be better than cutting.

https://www.permagrit.com/kt2/

Also cabinet scrapers seem to be a great tool to finish off edges.

I plan to start canopy soon, so I am very interested in this topic.

The recommendations in the construction manual were chosen for very specific reasons.
Largely out of experience helping builders try and recover from some level of catastrophy during their build.
It doesn't mean it is the only way but if you deviate, make sure you understand what you are doing.

Example - The purpose of starting with the window and roll bar at # 36 is to help builders get a properly aligned tap. This helps alleviate broken taps and crooked holes (both cause their own different problems)
#40 is bigger than # 36. If you start with 40 in the window you have another potential for misaligned holes (more problems).

The thing to keep in mind drilling acrylic is that a standard drill bit wants to pull through the soft material like a screw. It does it even worse if you are enlarging an existing hole.
The way to minimize problems is to only drill with a tool that primarily uses a scraping action to remove material (like a step drill or plexi drill)
You can modify any regular drill bit to remove material this way. A search on line will provide a lot of how too information.
 
Scott,

Just to follow up, the Vans construction manual recommends using a reamer to enlarge the canopy holes (or a unibit) in paragraph 5.19. Does the reamer not cut in a very similar manner as the unibit?

Any comments on that? I happen to have a #36 and a #27 straight flute reamer.

I will drill some practice pieces and see what it does when I get home.

Thanks for your comments.
 
Scott,

Just to follow up, the Vans construction manual recommends using a reamer to enlarge the canopy holes (or a unibit) in paragraph 5.19. Does the reamer not cut in a very similar manner as the unibit?

Any comments on that? I happen to have a #36 and a #27 straight flute reamer.

I will drill some practice pieces and see what it does when I get home.

Thanks for your comments.

Yes, a reamer has similar cutting action as a step drill which is why both are recommended as options.
As mentioned, drill bits can be easily modified to cut in a similar way as well, though they do require care because the spiral flutes are still bale to grab the material and draw it in, if you don't maintain alignment.
 
Any reason that these numbered drill (plexi-point) bits can't be used to enlarge holes? Or will they cause chipping? The #40 worked well for the initial drilling of the back window.

https://www.abbeon.com/Item--i-2118

For enlarging the hole from #40 to #36 for the roll bar side of the window, would the #36 plexiglass-point be OK for this job, since it will be enlarged to #27 anyway later? Or is a #36 reamer required?

Also, for final drilling to #27 for all the holes, would a plexi-point be OK, since one will be backing up the hole with a piece of wood? Or would a step bit be better, even though the hole would be bigger 5/32". Of course fo rate back holes, I doubt that there is a step bit that would initial fit into the #40 holes.
 
not sure if this is a good or bad idea as a method to clean up chipped holes, but would acrylic glue work, like TAP acrylic cement, help clean up the hole edges. The solvents would soften up the edges and the monomer would polymerize and "seal" the micro cracks as the solvent evaporates.

I am pretty sure that the glue works by partially dissolving up the surface of the polymer (swelling) and allows the two piece (when bonding acrylic edges together) to chain entangle and bond after the solvent evaporates.

I have not tried, but from a chemistry perspective it should.

You would have to be careful to not get the glue on any place that would be visible, since it might cause visual distortion due to the monomer in the glue.
 
Any reason that these numbered drill (plexi-point) bits can't be used to enlarge holes? Or will they cause chipping? The #40 worked well for the initial drilling of the back window.

https://www.abbeon.com/Item--i-2118

For enlarging the hole from #40 to #36 for the roll bar side of the window, would the #36 plexiglass-point be OK for this job, since it will be enlarged to #27 anyway later? Or is a #36 reamer required?

Also, for final drilling to #27 for all the holes, would a plexi-point be OK, since one will be backing up the hole with a piece of wood? Or would a step bit be better, even though the hole would be bigger 5/32". Of course fo rate back holes, I doubt that there is a step bit that would initial fit into the #40 holes.
I used this type of drill bit for an existing hole (#40) and had zero issues. I just wish I knew of a source that sold these type of drill in a numbered size. The hole that they produce is absolutely great and clean. I got mine from Tap plastic.
 
Enlarging Plexiglas Holes

For the back window, I initially drilled the Plexiglas with a 3/32 plexi-drill. Then I reamed to #40 then to #36. After tapping, I then reamed to #30 and finally to #27. The plexi-drill cut OK into the roll bar for the initial hole and the reamers did also for the later enlargements.

It was about 85 degrees in my shop and I noticed no chipping. This was my first time working with the Plexiglas. I was paranoid based on all the emails and tried to enlarge a little at a time.

It may have been overkill using all the reamers, but it seemed to work for me.
 
14 window drilling

Of all the posts I've read regarding drilling into plexi, this is the one I am going with. I am also very paranoid about the process.

Just ordered the #40 plexi bit, along with a #36 & #27 reamer.
Planning to order some scrap to practice with, then crank up the heat in the shop and get-r done.

Thanks to all for the posts.
 
When using reamers in metal, I've always done it by hand. For plexiglass, can you chuck it up in a drill and use a slow speed?

JH
 
I had good luck starting all holes with a standard #40 drill bit. Light pressure to avoid breaking through and chipping as you are seeing. You want to go slow so that you are generating a lot of heat at the tip. This helps soften the plexi a bit. After #40, upsize with a unibit. Not one chip or crack on the whole canopy.

Larry
 
I had good luck starting all holes with a standard #40 drill bit.

We tested a lot of different ways on scrap.

New, sharp bits can grab instantly (even when going slow) resulting in a nice long crack and a very bad day.

I recommend only using a very dull bit here.

You can dull a bit by just drilling 4 or 5 times into a brick.

To echo what everyone else is saying, it's the heat that makes the hole nice and clean.
 
Of all the posts I've read regarding drilling into plexi, this is the one I am going with. I am also very paranoid about the process.

Just ordered the #40 plexi bit, along with a #36 & #27 reamer.
Planning to order some scrap to practice with, then crank up the heat in the shop and get-r done.

Thanks to all for the posts.

Where did you find a #40 plexi bit?
 
Drilling plexi

I only drilled one hole in my canopy so not a huge amout of experience.
I used plexi bits to start up through the biggest I had then moved to reamers. I finished the last step with a unibit. The reamers were very smooth.
One tip I would suggest is use a drill with an adjustable clutch like a cordless. Turn it way down. If the bit tries to catch, the clutch will slip much quicker than you can release the trigger. Not sure it will prevent a problem but it made me feel safe.
 
The best plexiglass bit

Meant for composites, and spendy, but these will drill perfect plexiglass holes in -10F conditions with heavy pressure. Of course, don?t actually do that, but the design of the bit is that forgiving of technique. But I did test them on plexi cold soaked in a freezer.

https://www.browntool.com/Listview/tabid/344/ProductID/3089/Default.aspx

Or

https://www.yardstore.com/solid-carbide-tapered-drill-reamer-40

The design is a four fluted, multi-tapered reamer with a sharp point that terminates as a straight reamer.
 
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