Howzit? Thanks, the method worked for me, almost seems too easy. Shifting spanner, bench vise, 8mm allen socket, power bar - cracked it loose anti clockwise. Replaced with Dewalt / Rohm chuck
Hi Andre, thanks for the comment… I think mine is just really tight. Good to know that others are able to get theirs off relatively easily. How much was the now Chuck?
Hi Grant what a great video! I am an amateur repair guy who makes videos too. Thanks for the attempt at removing the chuck these are an absolute nightmare. I learned alot from your efforts. Liked and subscribed
Hi Doctor Lefthandthread, thanks very much. Some people are able to remove their chucks more easily than others (not in my case... haha). Good luck with your channel, I see you are almost at 1000 subs... keep it up.
@@doctorlefthandthread Same mostly goes for DIY projects… sometimes while completing a project, it may seem like time wasted but as soon as something new is created, it all seems to be worth the trouble and effort.
I had the same issue on these new DeWalt drills , chucks are held on with some serious industrial thread lock , I heated the internal chuck and applied penetrating oil and it broke free with a breaker bar , took 3 attempts with heat but worked ,
I removed chuck with attached spindle from dcd791. I cut it with angle grinder to access screws below chuck. Chuck is attached to “SPINDLE SA N438918”. So, I bought another spindle, “SPINDLE SA N110038”. It is used on earlier dcd790 drill but fits on dcd791 also. So now, I can use any standard chuck with central screw. So, I suppose that similar can be done with dcd796, replacing "Spindle N438748" with "Spindle Sa N110039" used for dcd795.
Hi Dejan, thanks for the comment. I'm pretty sure that during assembly the spindly is installed into the housing and then the three screws are fastened and after that, the chuck is installed onto the spindle (else how would one fasten the screws if the spindle and chuck are not separable?) Unless once the chuck has been installed for the first time onto the spindle, those somehow form a single unit which is inseparable. I may be wrong... just a guess. Good idea to buy a suitable spindle that can accept a central locking screw... makes life a bit easier for chuck replacement. Thanks for those part numbers, much appreciated.
@@GrantBurton Regarding what I saw in another video, where chuck was succesfully removed and seperated from spindle, I think it may be possible to drill the spindle and make a tread...
I found an easier way to remove chuck: I put a vicegrip on bottom of chuck and hitted down with a hammer a few times and came off within a couple minutes. Descubri una forma mucho mas facil y rapida de quitar el broquero: puse unas pinzas vicegrip en la parte de abajo del broquero y le pegue varias veces con un martillo hacia abajo y salio en menos de 2 minutos.
Hi Truman, thanks for the comment. It’s not so bad if a person just takes things slow and step by step, keep each part in a container of sorts and follow some sort of order. Also, don’t be like me in the past and place all your parts in separate containers, all nicely sorted… and then by mistake kick the table and everything goes flying… haha. Keep well.
Hi Grant, great video and well done for not getting frustrated! I've been repairing tools for almost 35 years now a think it's a real shame that all the manufactures seem to be making their cordless tool almost impossible and or uneconomical to repair and this is just another example of it. I never really saw any issues with the left hand screw down the middle, soak it in something like WD40 then simply unscrew it whip the chuck off and fit a new one. I've watched your video thinking could I be arsed to go to all that trouble and would a customer be willing to pay the labour for this to be done on a drill that retails for around £65 including taxes in the UK!? More plastic in the ground forever!
Hi MB Plant, thanks for the comment... I think in this case... 'the bigger the problem, the bigger the hammer' would likely end badly 😂😂 I would think designed obsolescence would work towards ensuring future sales. I'm sure you have a wealth of repair experience with 35 years under your belt. From the customers side, I don't think it's worth paying the labour for somebody else to repair since labour is getting very expensive these days... better to buy a new drill in this case BUT if a person is able to repair it themselves, It may be worth it.
Just bought a new 796 and out the box the chuck wobbles,and here i am already looking for a repair for a top brand, that cost a lot. Returned first one ,got another one and same problem. Will return it for good
Hi Darius, thats not great news... but also not the first time I've heard of the wobbly chuck on a new Dewalt drill.Quite a bit of a letdown. Are you going to go with a Milwaukee or Makita drill or stick to Dewalt but a different model... maybe the 996 or 998?
It is because of this, a bit being stuck in my chuck with no way to change the chuck, easily, because i broke it, trying to loose it with a vice. I will be buying a different brand next go around.
Hi Grant. There’s a special jig that DEWALT recommends to help you take the chuck off. We made a similar jig , so I’ll try to make a video of it and post it in our channel
Hi Zain, thanks for the info. Another person also commented a while back about this tool... I think they even gave a link where to purchase one. If I recall correctly, it's also not expensive.
hello friend! mine is always on the hammer, even when I'm screwing it in... I've disassembled all of it except for that part, do you think it could be that part of the tip?
Hi Zizo, I actually tried turning it in both directions to crack it loose (just in case) but no luck. From what others have said, turning the chuck anti-clockwise will loosen / unscrew it from the shaft. I'll give it another try sometime soon. Thanks for the comment.
Yo tenia el mismo problema con mi taladro estube leyendo algunos comentarios y veo que en algunos casos se puede retirar de manera muy fácil y em otros no... Mi caso era el difícil pero al fin lo logre Lo que hize cuando llegue hasta el punto donde ya no se pudo hacer nada en este video fue esto: le di algunos golpes a la flecha o eje sosteniendolo con la mano y ja ja salio el eje con el chuck y ya estando ahí con un soplete calenté un poco la flecha y salió la rosca sin nada de esfuerzo para volver a colocar la flecha fue a la inversa golpeando o presionando la flecha hacia adentro... Pienso que tal vez no se tenga que desarmar en su totalidad para sacar la flecha tal vez solo hacer presión como cuando sacas un valero o rotula de un vehículo.. Lo intentaré así más adelante Espero que a alguien le sirva esta info
Greetings from Sydney Aust! Have the same model. Luv it only had mine for about 3 years. Dewalt sure makes it hard for one to replace the chuck. What was wrong with the old method of an internal nut/bolt from the front? Also meant to ask is it normal for the chuck to have a bit of forward & backward freeplay like mine? It seems like there is a spring behind the chuck for some reason.
Hi Mike, both of my 796's have a slight bit of spring forward / backward freeplay. Not sure exactly why its there, haven't really given it much thought. Still loving them, use both quite often. Do you have other Dewalt tools?
I have the exact model. Was giving me some issues a couple days back it was seized up. The chuck was opened up right away. All I did was use a vice grip and turn it anti clockwise. And it's off.
Hi Sean, thanks for the reply. It seems like some people are able to remove their chucks pretty easily and some not so easily... haha. I'll give mine another go soon. Do you have any photos of it off?
Hi interman, thanks... I'll have a look for it and link it in the description. Thanks for always commenting on my videos, hope you are enjoying them. Hopefully I haven't missed replying to any of your comments... I don't seem to get notifications about all comments that come through when they are already part of a previous reply so some slip through the cracks. Keep Well.
Hi, good to hear yours came off so easily... some have reported also getting their off easily and other have also battled like me. Did you replace it with the same chuck or something different?
Hi GemLeo, thank for the comment. You are correct, normally the centre locking screw / bolt inside a chuck is reverse thread (left hand thread) however the spindle on these DeWalt drills does not have a central locking bolt / screw... the chuck is threaded onto the spindle with a normal right hand thread only, so what can be seen in the video is me trying to turn the chuck counter-clockwise in order to loosen it from the spindle. I wasn't able to get mine loose however others have said that theirs came loose pretty easily... maybe the thread locker on mine is just holding really tight.
ok so ive managed to remove my old chuck and put on a new one , you need to place the housing in a vice the punch out the spindle with the old chuck on it, the place the spindle with the old chuck in to a vice and heat up the spindle at the back of the chuck then crack its comes undone with a long bar.
This is exactly what I did and then it unscrewed nicely (anticlock) with a bit of love. Just getting all back together was the pain. All the gears and pins etc. It now is in permanent hammer so will pull it apart again tomorrow!
@@nickstaaa Hi Nick, Thats not great... always a bummer when you put something back together and it doesn't work properly because of a simple assembly error (assuming it was an assembly error, maybe not?). Hope you got it working properly again?
I Don't think it was meant to be taken off. I bet the chuck is pressed in to that bearing with the shaft. The inner shaft may be one piece with the chuck. Maybe pressing it off that bearing from the back. Who knows.
I think I'll try tearing it down again soon and press the shaft out from the back. Once thats out we could throw some heat across it, hopefully softening the thread locker.
Why doesn't this drill has a locking screw in the chuck? Is there a technical reason for that? Does they made it without the screw because the "neck" of the drill needs to be stronger? I guess a hollow neck to allow space for the screw might make it weaker...
Hi Paulo, thanks for the comment. I'm not exactly sure why the drill and chuck assembly were designed in this way but if I were to guess, one reason could be for cost saving. Not having a locking screw equates to an additional cost that can be saved on a screw / fastener and not having to drill / machine a hole in the end of the shaft and not having to form threads in that hole saves on machining and process costs... It might not sound like a big saving on one drill but when you multiply that small saving by hundreds of thousands of units, it equals to a large saving. And yes, I also agree... it probably is a bit stronger because its a solid shaft.
@@GrantBurton I wouldn't guess it is because of cost saving, because, at least in the Dewalt power tools, they seam use them on their most expensive and stronger models. I have a D21570k, and it annoys me that it doesn't come with that screw, and it is one of the most expensive Dewalt corded drills available here in Brazil. I hope they make it that way because of some performance enhancement, instead of just cutting prices down, but then again, many cheap "made in China" chucks doesn't have fasteners also, and probably just to lower their costs.
@@paulopaniago9874 I was thinking along the lines of cost saving on various parts not necessarily being a bad thing... If they are able to save some costs on one part (without reducing reliability / strength), they might be able to spend that saving elsewhere on the tool, so overall they are able to improve quality without increasing cost of the tool, or at least maintain the cost of the tool as production / material costs increase over time. Who knows... I guess thats the continual balance between engineers and the money police (aka accountants)... haha.
@@paulopaniago9874 Hopefully over time, the video gets shared and more people see and read the comments... maybe they read our conversation and are able to give their comment on the screw.
Hi Dejan, thanks for those part numbers... Looks fairly simple to fabricate those tools. I can see how the 559697-99 tool works... to adapt the back of the spindle to a hex for a socket but from the one picture I saw of the 559661-99 tool... how does that work? I assume that holds the front side of the chuck in some way?
@@Pete1965 Hi Peter, what Brand did you end up going with? Makita and Milwaukee also make some good quality tools. I've got a Makita Jig saw and an Abrasive Cut-off saw and they are both awesome machines.
Please don't do that. Open the jaws fully, and look down the throat. You'll see a bolt head, usually either Allen key or torx. It's got a left hand thread, so undo in reverse, and remove. Then using the jaws of the chuck insert an Allen key just like you did. Grasp the key in a vice and use the drill to unwind it's chuck (normal right hand thread).
Hi, thanks for the comment... Most chucks are secured in the way you describe (with the central Allen key or torx) however this model of Dewalt drill is different. Turns out it doesn't have a central locking screw, but rather just normal thread on the chuck and high strength threadlocker.
![TEARDOWN Dewalt XR DCD796 20v MAX Brushless Drill - Burton Builds S03E04 [4K]](http://i.ytimg.com/vi/i_dQjMNCUqY/mqdefault.jpg)
Howzit? Thanks, the method worked for me, almost seems too easy. Shifting spanner, bench vise, 8mm allen socket, power bar - cracked it loose anti clockwise.
Replaced with Dewalt / Rohm chuck
Hi Andre, thanks for the comment… I think mine is just really tight. Good to know that others are able to get theirs off relatively easily. How much was the now Chuck?
Hi Grant, the Dewalt DT7043QZ chuck was AU$48 from Amazon
@@ab678 cool, not to expensive then.
Hi Grant what a great video!
I am an amateur repair guy who makes videos too.
Thanks for the attempt at removing the chuck these are an absolute nightmare. I learned alot from your efforts. Liked and subscribed
Hi Doctor Lefthandthread, thanks very much. Some people are able to remove their chucks more easily than others (not in my case... haha). Good luck with your channel, I see you are almost at 1000 subs... keep it up.
@@GrantBurton Thanks for the reply, repairs can be frustrating when it doesn't go 100% but when it goes well very rewarding.
@@doctorlefthandthread Same mostly goes for DIY projects… sometimes while completing a project, it may seem like time wasted but as soon as something new is created, it all seems to be worth the trouble and effort.
@@GrantBurton Thanks for the chat and I will have a look on your channel to see if I can get any more tips 👍
I had the same issue on these new DeWalt drills , chucks are held on with some serious industrial thread lock , I heated the internal chuck and applied penetrating oil and it broke free with a breaker bar , took 3 attempts with heat but worked ,
Hi Kerry, thanks for letting us know. Much appreciated
I removed chuck with attached spindle from dcd791. I cut it with angle grinder to access screws below chuck. Chuck is attached to “SPINDLE SA N438918”. So, I bought another spindle, “SPINDLE SA N110038”. It is used on earlier dcd790 drill but fits on dcd791 also. So now, I can use any standard chuck with central screw.
So, I suppose that similar can be done with dcd796, replacing "Spindle N438748" with "Spindle Sa N110039" used for dcd795.
Hi Dejan, thanks for the comment. I'm pretty sure that during assembly the spindly is installed into the housing and then the three screws are fastened and after that, the chuck is installed onto the spindle (else how would one fasten the screws if the spindle and chuck are not separable?) Unless once the chuck has been installed for the first time onto the spindle, those somehow form a single unit which is inseparable. I may be wrong... just a guess.
Good idea to buy a suitable spindle that can accept a central locking screw... makes life a bit easier for chuck replacement. Thanks for those part numbers, much appreciated.
is it not removable without cutting?
@@GrantBurton Regarding what I saw in another video, where chuck was succesfully removed and seperated from spindle, I think it may be possible to drill the spindle and make a tread...
I found an easier way to remove chuck:
I put a vicegrip on bottom of chuck and hitted down with a hammer a few times and came off within a couple minutes.
Descubri una forma mucho mas facil y rapida de quitar el broquero: puse unas pinzas vicegrip en la parte de abajo del broquero y le pegue varias veces con un martillo hacia abajo y salio en menos de 2 minutos.
Thanks very much 👍
I had a 1meter long lever arm and still took quite a load on the end to loosen. Scary but the shaft did not break.
Wow, thats a long arm... plenty of power behind that. Thanks for the comment.
I had the same problem I used a 5-ft bar to try and break it loose and I went harder on it than you did. Still no luck.
I must have another go at getting mine loose. Thanks for the comment.
DAYUM This is way harder than I'm going to risk. I'll lose a part and make it worthless otherwise. :) Thanks!
Hi Truman, thanks for the comment. It’s not so bad if a person just takes things slow and step by step, keep each part in a container of sorts and follow some sort of order. Also, don’t be like me in the past and place all your parts in separate containers, all nicely sorted… and then by mistake kick the table and everything goes flying… haha. Keep well.
Hi Grant, great video and well done for not getting frustrated! I've been repairing tools for almost 35 years now a think it's a real shame that all the manufactures seem to be making their cordless tool almost impossible and or uneconomical to repair and this is just another example of it. I never really saw any issues with the left hand screw down the middle, soak it in something like WD40 then simply unscrew it whip the chuck off and fit a new one. I've watched your video thinking could I be arsed to go to all that trouble and would a customer be willing to pay the labour for this to be done on a drill that retails for around £65 including taxes in the UK!? More plastic in the ground forever!
Hi MB Plant, thanks for the comment... I think in this case... 'the bigger the problem, the bigger the hammer' would likely end badly 😂😂 I would think designed obsolescence would work towards ensuring future sales. I'm sure you have a wealth of repair experience with 35 years under your belt.
From the customers side, I don't think it's worth paying the labour for somebody else to repair since labour is getting very expensive these days... better to buy a new drill in this case BUT if a person is able to repair it themselves, It may be worth it.
Tap it out from the gearbox housing. Apply some heat to soften the thread lock. Then do what you did.
Awesome, thanks very much for the advice.
Just bought a new 796 and out the box the chuck wobbles,and here i am already looking for a repair for a top brand, that cost a lot. Returned first one ,got another one and same problem.
Will return it for good
Hi Darius, thats not great news... but also not the first time I've heard of the wobbly chuck on a new Dewalt drill.Quite a bit of a letdown. Are you going to go with a Milwaukee or Makita drill or stick to Dewalt but a different model... maybe the 996 or 998?
@@GrantBurton i like dewalt and i am getting diffrent other 18 v tools. i ordered a 996 if doesn't have the same problem will keep it.
Cool beans... please let us know how it goes with the 996.
It is because of this, a bit being stuck in my chuck with no way to change the chuck, easily, because i broke it, trying to loose it with a vice. I will be buying a different brand next go around.
Hi Grant. There’s a special jig that DEWALT recommends to help you take the chuck off. We made a similar jig , so I’ll try to make a video of it and post it in our channel
Hi Zain, thanks for the info. Another person also commented a while back about this tool... I think they even gave a link where to purchase one. If I recall correctly, it's also not expensive.
hello friend! mine is always on the hammer, even when I'm screwing it in... I've disassembled all of it except for that part, do you think it could be that part of the tip?
Hello. You try turn in left direction, but you shold turn right.
Hi Zizo, I actually tried turning it in both directions to crack it loose (just in case) but no luck. From what others have said, turning the chuck anti-clockwise will loosen / unscrew it from the shaft. I'll give it another try sometime soon. Thanks for the comment.
Yo tenia el mismo problema con mi taladro estube leyendo algunos comentarios y veo que en algunos casos se puede retirar de manera muy fácil y em otros no... Mi caso era el difícil pero al fin lo logre
Lo que hize cuando llegue hasta el punto donde ya no se pudo hacer nada en este video fue esto: le di algunos golpes a la flecha o eje sosteniendolo con la mano y ja ja salio el eje con el chuck y ya estando ahí con un soplete calenté un poco la flecha y salió la rosca sin nada de esfuerzo para volver a colocar la flecha fue a la inversa golpeando o presionando la flecha hacia adentro... Pienso que tal vez no se tenga que desarmar en su totalidad para sacar la flecha tal vez solo hacer presión como cuando sacas un valero o rotula de un vehículo.. Lo intentaré así más adelante
Espero que a alguien le sirva esta info
Hi Ruben, Gracias por el comentario. Su información es muy útil... gracias.
Greetings from Sydney Aust! Have the same model. Luv it only had mine for about 3 years. Dewalt sure makes it hard for one to replace the chuck. What was wrong with the old method of an internal nut/bolt from the front? Also meant to ask is it normal for the chuck to have a bit of forward & backward freeplay like mine? It seems like there is a spring behind the chuck for some reason.
Hi Mike, both of my 796's have a slight bit of spring forward / backward freeplay. Not sure exactly why its there, haven't really given it much thought. Still loving them, use both quite often.
Do you have other Dewalt tools?
Think the fore and aft movements is for the hammer action, to absorb some of the impact to make it more comfortable for the user.
I have the exact model. Was giving me some issues a couple days back it was seized up. The chuck was opened up right away. All I did was use a vice grip and turn it anti clockwise. And it's off.
Hi Sean, thanks for the reply. It seems like some people are able to remove their chucks pretty easily and some not so easily... haha. I'll give mine another go soon. Do you have any photos of it off?
drive.google.com/file/d/1-30QU10t1SD5tyqyhJ4aUIaY_EiCpWzS/view?usp=drivesdk
That's it. I can't find the removed chuck at the moment. I am planning on replacing it with a chuck from the dcd996.
@@seanabraham8432 thanks for the photo. Mine must just be super tight with thread locker.
Gidday from Oz Grant ,btw there is fellow on YT that takes the chuck off of a 996 ,it might be worth a look .
Hi interman, thanks... I'll have a look for it and link it in the description.
Thanks for always commenting on my videos, hope you are enjoying them. Hopefully I haven't missed replying to any of your comments... I don't seem to get notifications about all comments that come through when they are already part of a previous reply so some slip through the cracks. Keep Well.
Got mine off a few minutes ago took all of 2 minutes a 12mm allen key and a bench vice
Hi, good to hear yours came off so easily... some have reported also getting their off easily and other have also battled like me.
Did you replace it with the same chuck or something different?
@@GrantBurton dewalt 7043-qz works great, I held the allen key in the vice and spun the drill it worked pretty easy
@@JOHNNYGEORGE22 Awesome, and thanks for the reply.
Hey, my drill chuck jammed and cannot tight or loose. How to use this method then?
Hi, have you tried spraying a bit of penetrating oil into the chuck?
Hey the chuck retaining bolt is reverse thread. You were tightening it more and more! 😂
Hi GemLeo, thank for the comment. You are correct, normally the centre locking screw / bolt inside a chuck is reverse thread (left hand thread) however the spindle on these DeWalt drills does not have a central locking bolt / screw... the chuck is threaded onto the spindle with a normal right hand thread only, so what can be seen in the video is me trying to turn the chuck counter-clockwise in order to loosen it from the spindle.
I wasn't able to get mine loose however others have said that theirs came loose pretty easily... maybe the thread locker on mine is just holding really tight.
Did your drill still work after you put it back together or were you just modelling all the outside bits stuck together there at the end?
Most definitely still working... haha.
ok so ive managed to remove my old chuck and put on a new one , you need to place the housing in a vice the punch out the spindle with the old chuck on it, the place the spindle with the old chuck in to a vice and heat up the spindle at the back of the chuck then crack its comes undone with a long bar.
Hi Ashdown, thanks for feedback, I may just give that a try next time I've got the drill open.
This is exactly what I did and then it unscrewed nicely (anticlock) with a bit of love. Just getting all back together was the pain. All the gears and pins etc. It now is in permanent hammer so will pull it apart again tomorrow!
@@nickstaaa Hi Nick, Thats not great... always a bummer when you put something back together and it doesn't work properly because of a simple assembly error (assuming it was an assembly error, maybe not?). Hope you got it working properly again?
I Don't think it was meant to be taken off. I bet the chuck is pressed in to that bearing with the shaft. The inner shaft may be one piece with the chuck. Maybe pressing it off that bearing from the back. Who knows.
I think I'll try tearing it down again soon and press the shaft out from the back. Once thats out we could throw some heat across it, hopefully softening the thread locker.
Why doesn't this drill has a locking screw in the chuck? Is there a technical reason for that? Does they made it without the screw because the "neck" of the drill needs to be stronger? I guess a hollow neck to allow space for the screw might make it weaker...
Hi Paulo, thanks for the comment. I'm not exactly sure why the drill and chuck assembly were designed in this way but if I were to guess, one reason could be for cost saving. Not having a locking screw equates to an additional cost that can be saved on a screw / fastener and not having to drill / machine a hole in the end of the shaft and not having to form threads in that hole saves on machining and process costs... It might not sound like a big saving on one drill but when you multiply that small saving by hundreds of thousands of units, it equals to a large saving.
And yes, I also agree... it probably is a bit stronger because its a solid shaft.
@@GrantBurton I wouldn't guess it is because of cost saving, because, at least in the Dewalt power tools, they seam use them on their most expensive and stronger models. I have a D21570k, and it annoys me that it doesn't come with that screw, and it is one of the most expensive Dewalt corded drills available here in Brazil. I hope they make it that way because of some performance enhancement, instead of just cutting prices down, but then again, many cheap "made in China" chucks doesn't have fasteners also, and probably just to lower their costs.
@@paulopaniago9874 I was thinking along the lines of cost saving on various parts not necessarily being a bad thing... If they are able to save some costs on one part (without reducing reliability / strength), they might be able to spend that saving elsewhere on the tool, so overall they are able to improve quality without increasing cost of the tool, or at least maintain the cost of the tool as production / material costs increase over time. Who knows... I guess thats the continual balance between engineers and the money police (aka accountants)... haha.
@@GrantBurton Oh, I haven't seen it that way, that is a very good argument, specially on the most expensive tools. Thanks Grand!!!
@@paulopaniago9874 Hopefully over time, the video gets shared and more people see and read the comments... maybe they read our conversation and are able to give their comment on the screw.
The proper way to remove drill chuck is to use “DeWalt S.t.chuck Removal Jig 559661-99” and “DeWalt S.t.insert 559697-99”
Hi Dejan, thanks for those part numbers... Looks fairly simple to fabricate those tools. I can see how the 559697-99 tool works... to adapt the back of the spindle to a hex for a socket but from the one picture I saw of the 559661-99 tool... how does that work? I assume that holds the front side of the chuck in some way?
@@Pete1965 Hi Peter, what Brand did you end up going with? Makita and Milwaukee also make some good quality tools. I've got a Makita Jig saw and an Abrasive Cut-off saw and they are both awesome machines.
This chuck untitens clockwise i think ;)
Cut it off
Hi Randy, haha… I might have to do that once the Chuck eventually breaks. Thanks for the comment though.
Please don't do that. Open the jaws fully, and look down the throat. You'll see a bolt head, usually either Allen key or torx. It's got a left hand thread, so undo in reverse, and remove. Then using the jaws of the chuck insert an Allen key just like you did. Grasp the key in a vice and use the drill to unwind it's chuck (normal right hand thread).
Hi, thanks for the comment... Most chucks are secured in the way you describe (with the central Allen key or torx) however this model of Dewalt drill is different. Turns out it doesn't have a central locking screw, but rather just normal thread on the chuck and high strength threadlocker.